Sewer Lining Process And Bypass Pumping: A Practical Guide

If you’re planning a sewer lining project, you can’t ignore one critical piece of the puzzle: how you’ll keep wastewater flowing while the pipe is offline. That’s where bypass pumping comes in.

Done well, bypass pumping lets you repair or rehabilitate a sewer line with minimal disruption to your property or community. Done poorly, or skipped altogether, it can create backups, overflows, angry neighbors, and serious regulatory headaches.

This guide walks you through how the sewer lining process works, why bypass pumping is often essential, and what you should expect from a well-designed, professionally managed project. Whether you’re a property owner, facility manager, contractor, or municipal engineer, you’ll get a clear, practical roadmap for doing sewer lining and bypass pumping the right way.

NuFlow is a leading trenchless pipe repair and rehabilitation company serving residential, commercial, and municipal properties. If you’re already dealing with plumbing problems, you can use this guide to understand your options and what to ask your contractor before work begins.

Understanding Sewer Lining And When It Is Needed

Sewer lining is a trenchless method of rehabilitating existing sewer pipes from the inside, rather than digging them up and replacing them. In most cases, you keep the original host pipe in place and add a new structural or protective layer inside it.

As a property owner or manager, you typically consider lining when the pipe is failing, but full replacement would be too disruptive, too expensive, or both.

Common Sewer Pipe Problems That Lead To Lining

You don’t usually wake up thinking, “I should line my sewer today.” You get pushed there by persistent or severe problems like:

• Recurring blockages and backups – Especially if you’ve had a drain cleaner out multiple times and the problem keeps returning in the same location.
• Root intrusion – Tree roots entering through joints or cracks, grabbing debris, and building “root balls” that choke flow.
• Cracked or fractured pipes – From ground movement, shallow cover, heavy traffic loads, or aging materials.
• Corrosion and tuberculation – In cast iron or steel lines, internal corrosion can create rough, constricted passageways and pinhole leaks.
• Infiltration and inflow (I/I) – Groundwater or stormwater entering the system through defects and joints, overloading the sewer and causing downstream capacity issues.
• Joint separation or misalignment – Common in older clay or concrete pipe: joints shift, creating ledges, offsets, and leak paths.
• Aging materials near end-of-life – When a system is 40–60+ years old and showing multiple issues, lining can extend its life without full rebuild.

Lining makes the most sense when:

• The pipe is structurally sound enough to host a liner (not completely collapsed).
• Access points (cleanouts, manholes) allow liners and bypass piping to be installed.
• Excavation would damage finishes, landscaping, pavement, or busy streets.

Trenchless Lining Methods Versus Traditional Replacement

Traditional “dig-and-replace” sewer repair means excavators, trenches, shoring, and days or weeks of disruption. You remove the old pipe and install a new one in its place. Sometimes, that’s the only option, like when a pipe has totally collapsed or moved badly out of alignment.

But whenever you can avoid excavation, trenchless lining has clear advantages:

• Minimal disruption – Instead of trenching through yards, driveways, foundations, streets, or sidewalks, you use existing access points plus a few small pits if needed.
• Lower total cost – When you factor in pavement, landscaping, and concrete restoration, trenchless methods can usually be 30–50% less than dig-and-replace.
• Faster completion – Many repair segments are completed in 1–2 days, not weeks.
• Long-lasting results – Quality cured-in-place pipe (CIPP) and epoxy lining systems are designed to last 50+ years when properly installed.

Common trenchless sewer lining methods include:

• CIPP (Cured-In-Place Pipe) – A resin-saturated liner (felt or fiberglass) is inserted into the host pipe, then cured with hot water, steam, or UV light to create a new, jointless pipe inside the old one.
• Epoxy coating/lining – Epoxy resins are applied to the interior of the pipe (often in smaller-diameter lines) to create a smooth, corrosion-resistant barrier.
• Segmental slip-lining and spiral wound liners – Used more in larger-diameter or municipal applications.

NuFlow specializes in trenchless technologies like CIPP lining, epoxy coating, and UV-cured pipe rehabilitation, helping you fix sewer lines, drain pipes, and water systems without major excavation. If you’d like to see how this works in the real world, you can browse NuFlow’s project results on our case studies page.

Why Bypass Pumping Is Critical During Sewer Lining

During sewer lining, you’re taking a section of pipe out of service, sometimes for many hours, occasionally for a day or more. Flow still has to go somewhere. If you don’t manage that flow, you can cause backups into buildings or overflows into streets, soil, or waterways.

That’s where bypass pumping comes in.

What Bypass Pumping Actually Does

A bypass pumping system temporarily reroutes wastewater or stormwater around the section being repaired. Conceptually, it’s simple:

1. You intercept flow upstream of the work area.
2. You pump or gravity-flow that water through temporary hoses or pipes.
3. You discharge it downstream of the work area, back into the system.

In practice, doing this safely and reliably involves:

• Choosing pumps that can handle the peak flow rate plus a safety margin.
• Setting up a suction intake upstream (often from a manhole or wet well).
• Running temporary discharge piping or hose along the ground or overhead to a downstream manhole.
• Using valves and controls to manage flow and prevent backflow.
• Monitoring the system and having contingency plans for power loss, pump failure, or storms.

While the bypass is running, your lining crew can:

• Clean and inspect the host pipe.
• Install and cure the liner.
• Reconnect services and perform final testing.

Situations Where Bypass Systems Are Mandatory

In some projects, bypass pumping is a smart idea. In others, it’s non-negotiable for safety and compliance. You typically need a bypass system when:

• The sewer carries continuous flow that can’t be shut off (most municipal lines, multi-unit buildings, hospitals, etc.).
• There’s no practical way to hold or store flow (no large equalization basins or alternate routing).
• Health and regulatory standards prohibit any overflow, especially near waterways, public spaces, or critical facilities.
• You’re working on main trunks or critical collectors where a backup would affect many customers, not just one building.
• You’re curing CIPP with water or steam and need a stable, dry environment inside the host pipe.

Even on small residential projects, bypass pumping may be needed if:

• The line serves multiple units or a busy commercial space.
• You can’t reasonably shut down usage for the required window.

In short: if you can’t guarantee that flows will be low enough or stoppable for the duration of work, you should plan on bypass pumping. Any reputable contractor or engineer will design this into the project from the start.

Key Components Of A Sewer Bypass Pumping System

A well-designed bypass pumping setup is more than “a pump and a hose.” Understanding the major components helps you ask better questions and spot cutting corners.

Pumps, Power, And Controls

Pumps are the heart of the system. For sewer bypasses, contractors typically use:

• Diesel-driven centrifugal pumps – Common for higher flows or remote sites.
• Electric submersible pumps – Used when power is available and noise must be minimized.

Critical considerations include:

• Capacity (GPM or MGD) – Pumps must comfortably handle peak flows with a safety factor (often 1.5–2.0x expected peak).
• Solids-handling capability – Sewer flows aren’t clean water: pumps must pass rags, grit, and debris without constant clogging.
• NPSH and suction conditions – To avoid cavitation and loss of prime.

For power and controls, a robust system should include:

• Reliable power source (utility power or appropriately sized generators).
• Automatic start/stop via level controls in the wet well or suction manhole.
• Alarm systems for high-level, pump failure, and power loss.
• Manual overrides and clear operating procedures.

Suction And Discharge Piping Layout

The suction side is where flow enters the pumps:

• Suction hoses or rigid pipe are placed into the upstream manhole or wet well.
• Trash racks or strainers help prevent large debris from reaching the pumps.
• Suction piping should be as short and direct as possible to reduce friction loss and priming issues.

The discharge side carries pumped flow to the downstream connection point:

• Typically high‑density polyethylene (HDPE) or lay-flat hose runs on or above ground.
• Piping is routed to avoid traffic hazards, tripping hazards, and interference with other utilities.
• Where the line crosses roads or driveways, crews may use ramps, trench plates, or temporary overhead supports.

Good layout design aims to:

• Minimize friction losses (fewer sharp bends, correct diameter).
• Protect the piping from damage by vehicles, equipment, or vandalism.
• Maintain access for your lining crew and normal site operations.

Valves, Check Valves, And Backflow Prevention

Valves and check valves are the “traffic cops” of the bypass system:

• Isolation valves allow sections of the line to be shut off for maintenance or reconfiguration.
• Check valves prevent reverse flow if a pump stops or if downstream pressure spikes.
• Pressure relief valves may be used to protect the system from over‑pressure.

Proper backflow prevention is critical to:

• Protect upstream manholes and structures from surges.
• Prevent flooding of excavation or work areas.
• Maintain control over where flows actually go.

Ask your contractor how they’re handling backflow prevention, isolation, and emergency shut-down in their bypass plan, it’s one of the best ways to gauge their attention to detail.

Planning The Sewer Lining Project With Bypass Pumping

Bypass pumping isn’t something you bolt on the day before lining. It should be integrated into your overall project planning.

Flow Monitoring And System Sizing

To size a bypass system correctly, your team needs to understand how much flow they’re dealing with, and when.

Key steps typically include:

• Reviewing historical data – For municipal systems, that may include SCADA records, pump run times, or flow meters.
• Short-term flow monitoring – Portable flow meters can be installed for days or weeks to capture diurnal patterns.
• Allowing for wet-weather events – Even if you plan to work in dry conditions, you need capacity for unexpected rain.

A good design will size pumps and piping to manage:

• Average daily flow,
• Typical peaks (morning and evening in residential areas), and
• A reasonable safety factor for unexpected spikes.

Site Constraints, Access, And Traffic Management

Every site is different. On a residential property, constraints might be landscaping, tight side yards, or driveways. On a municipal project, you may be dealing with busy roads, utility conflicts, and heavy traffic.

Your planning team should consider:

• Access to manholes and cleanouts for suction and discharge points.
• Space for equipment – Pumps, generators, hose runs, and liner installation equipment.
• Traffic impacts – Will you need lane closures, detours, or flaggers?
• Noise and odor – Especially near residential or commercial properties.

Often, a traffic control plan is required, including signage, barricades, and safe pedestrian routes. When you work with a trenchless specialist like NuFlow, we coordinate these elements so bypass pumping doesn’t create more disruption than the problem you’re fixing.

Permitting, Notifications, And Regulatory Requirements

Bypass pumping and sewer lining frequently trigger regulatory requirements, especially on public systems. You may need:

• Permits for temporary discharge or construction in the right-of-way.
• Traffic control approvals from the city or transportation agency.
• Notifications to affected customers about service impacts.
• Environmental protections to prevent spills to storm drains or waterways.

Municipal owners and public works teams often coordinate closely with trenchless contractors. If you’re in that role, NuFlow’s dedicated Municipalities & Utilities team can help design lining and bypass projects that meet your regulatory and community obligations.

Step-By-Step Sewer Lining Process With Bypass Pumping

While no two projects are identical, most sewer lining jobs that use bypass pumping follow a similar sequence. Understanding this helps you set realistic expectations and spot any shortcuts.

1. Site Assessment And CCTV Inspection

Everything starts with information.

• A crew conducts a CCTV (closed-circuit TV) inspection of the existing pipe.
• They document pipe material, diameter, length, and condition.
• Defects, cracks, offsets, roots, corrosion, infiltration, are mapped and measured.

At the same time, they evaluate:

• Access points (manholes, cleanouts, mechanical rooms).
• Bypass routing options (where pumps and hoses can be placed safely).
• Any constraints like overhead power lines, narrow corridors, or traffic.

From this, your contractor or engineer develops a lining design and bypass pumping plan.

2. Cleaning And Preparing The Existing Sewer

Before you can line a pipe, you need a clean, stable surface.

Typical prep includes:

• High-pressure water jetting to remove grease, roots, and debris.
• Mechanical cutting of severe root masses, protruding taps, or deposits.
• Final CCTV inspection to confirm the pipe is ready and dimensions are accurate.

If the host pipe has severe defects (voids, missing sections, or structural failures), spot repairs or stabilization may be needed before lining.

3. Installing And Commissioning The Bypass System

Next, the bypass system is installed so the lining crew can work in a dry, controlled pipe.

Key steps:

• Set pumps at the upstream manhole or wet well.
• Lay out suction and discharge piping according to the design, securing crossings and protecting the public.
• Install valves, check valves, and connections at the upstream and downstream tie-in points.
• Connect power, controls, and alarms for the pumps.

Before main work begins, the system is tested:

• Flows are ramped up to expected operating conditions.
• Staff confirms no leaks, stable prime, and proper operation of controls and backup systems.
• Operators verify that all flows are being captured and discharged downstream, with no overflows.

Only once the bypass is running reliably is the lined segment taken out of service.

4. Installing The Liner (CIPP Or Other Methods)

With flows bypassed, the lining work moves quickly.

For CIPP lining:

• The liner tube is saturated with a thermosetting resin (often polyester, vinyl ester, or epoxy).
• It’s inserted into the host pipe, usually by inversion (using water or air pressure) or pull-in methods.
• Once in place, it’s pressurized to conform tightly to the host pipe and hold shape.

For epoxy lining in smaller-diameter building drains:

• Surfaces are prepped and dried thoroughly.
• Epoxy is applied (sprayed or pulled) in controlled thicknesses.
• Multiple coats may be applied for a fully sealed, corrosion-resistant interior.

NuFlow frequently uses UV-cured CIPP and epoxy-lined systems that minimize curing time and disruption, especially in occupied buildings.

5. Curing, Cooling, And Final Liner Inspection

The liner must now be cured to become a rigid, long-lasting pipe.

Curing methods include:

• Hot water or steam curing – Common in many CIPP installations.
• UV light curing – A UV light train is pulled through the liner to initiate rapid, controlled curing.

During curing, the contractor monitors:

• Temperature and pressure inside the liner.
• Cure time according to manufacturer specifications.

After curing:

• The liner is allowed to cool and depressurize.
• End seals and transitions are installed as needed.
• A post-lining CCTV inspection is performed to confirm:
• Full coverage and tight fit.
• No wrinkles or significant defects.
• Openings for service laterals are reinstated (for mainline work).

This inspection becomes part of your permanent record of the repair.

6. Decommissioning The Bypass And Site Restoration

Once the liner is accepted:

• Flow is gradually returned to the rehabilitated pipe.
• The bypass pumps are shut down and disconnected.
• Temporary hoses, pipes, ramps, and safety barriers are removed.

Finally, the contractor restores the site:

• Any small access pits are backfilled and compacted.
• Pavement, landscaping, or interior finishes disturbed during work are restored.

Because trenchless lining minimizes excavation, restoration is typically limited and fast, one of the major reasons many owners choose this option in the first place.

Design Considerations For Reliable Bypass Pumping

Bypass systems must work 100% of the time while your sewer is offline. There’s no acceptable “downtime” when you’re dealing with raw wastewater.

Redundancy, Backup Power, And Emergency Capacity

Reliable systems are built with layers of protection, not wishful thinking.

Smart design often includes:

• Multiple pumps in parallel – So if one fails, the others can carry the load.
• Standby pumps – A backup unit connected and ready to start automatically if needed.
• Backup power – Generators sized to start and run all pumps under load.
• Fuel management plans – So generators and diesel pumps don’t run out of fuel mid-project.

Emergency capacity planning considers:

• What happens if one pump fails at peak flow.
• How crews will respond to blocked suction (debris, rags) or discharge line damage.
• Whether there is enough storage or contingency plan to handle short disruptions without overflows.

Managing Peak Flows And Wet-Weather Events

Peak flows are predictable: storms aren’t.

Your bypass design should:

• Account for diurnal flow cycles (morning/evening usage spikes).
• Consider weekend vs. weekday patterns in commercial or institutional buildings.
• Include contingencies if rain or snowmelt dramatically increases flow.

On municipal projects, contractors and owners often:

• Schedule bypass work during dry-weather windows.
• Have rental or surge pumps on call if forecasts change.
• Use temporary storage tanks or basins if justified by risk.

Noise, Odor, And Environmental Controls

Even a perfectly functioning bypass can create issues if you ignore the surroundings.

Good practice includes:

• Noise control – Using sound-attenuated pump enclosures, placing equipment away from sensitive receptors, and scheduling loud activities during acceptable hours.
• Odor management – Keeping manhole covers closed where possible, using odor control filters or temporary venting if needed.
• Spill prevention – Secondary containment under pumps and fuel tanks, drip pans, and regular checks for leaks.

For projects in residential neighborhoods, hospitals, hotels, or campuses, these details make the difference between a smooth project and a flood of complaints.

Safety And Risk Management On Bypass Pumping Sites

Sewer lining and bypass pumping combine typical construction hazards with unique risks from confined spaces and wastewater. A serious contractor will treat safety as central, not optional.

Confined Space, Traffic, And Public Safety

Key risks include:

• Confined space entry into manholes or vaults, which requires training, gas monitoring, ventilation, and rescue plans.
• Vehicle and pedestrian traffic near pump setups and hose crossings.
• Public access to hoses, pits, and temporary equipment.

To manage these risks, your contractor should:

• Follow confined space entry regulations and have documented procedures.
• Provide proper barricades, cones, and signage around work zones.
• Use ramps or covers where hoses cross sidewalks or drive lanes.
• Keep the public physically separated from hazardous areas.

Spill Prevention And Contingency Planning

Even with careful design, things can go wrong. Responsible teams plan for that.

Elements of good spill prevention and response include:

• Secondary containment for pumps and fuel systems.
• Quick-disconnect fittings and robust hose connections to reduce leaks.
• On-site spill kits and trained staff who know how to use them.
• A written contingency plan that addresses:
• Pump failure or power loss.
• Hose or pipe rupture.
• Unexpected flow surges.

In many jurisdictions, serious spills must be reported to environmental or health agencies, so contractors design systems to avoid that scenario at all costs.

Monitoring, Alarms, And On-Site Supervision

A bypass system should never be a “set it and forget it” operation.

Best practice is to have:

• Continuous level monitoring at upstream structures.
• Alarms for high levels, pump faults, and power failure.
• On-site or on-call supervision 24/7 while the bypass is active, especially on critical lines.

Ask explicitly how your provider will monitor the system overnight and on weekends. If the answer is vague, that’s a red flag.

Cost Factors And Project Optimization

Sewer lining with bypass pumping is an investment, but careful design and planning can keep costs under control while minimizing disruption.

Major Cost Drivers In Lining And Bypass Work

Major cost elements usually include:

• Length and diameter of pipe to be lined.
• Number and complexity of access points (manholes, cleanouts, pits).
• Type of lining system (CIPP vs. epoxy coating vs. other methods).
• Bypass pumping duration and capacity required.
• Traffic control and site constraints (busy road vs. open field).
• Permitting and regulatory requirements.

Bypass-specific costs are influenced by:

• Pump size and quantity.
• Length and diameter of temporary piping.
• Power needs (generators vs. grid power).
• Required staffing and monitoring level.

Strategies To Reduce Downtime And Community Impact

You can often lower both direct and indirect costs by reducing downtime and community impact.

Effective strategies include:

• Thorough pre-planning – Good design prevents last-minute changes that drag out a project.
• Choosing efficient curing methods – UV-cured CIPP or fast-curing epoxy can reduce bypass duration.
• Scheduling during off-peak times – Nights, weekends, or school breaks where appropriate.
• Coordinating multiple repairs in one mobilization – Once the bypass is set up, you may be able to rehabilitate multiple segments.

NuFlow’s trenchless methods are specifically geared toward minimal disruption. Many projects are completed within 1–2 days, avoiding the extended lane closures and weeks-long excavation typical of dig-and-replace.

Working With Specialized Contractors And Engineers

Not all contractors have the same level of experience with trenchless lining and bypass pumping. When you evaluate potential partners, look for:

• Demonstrated experience with similar pipe sizes and project types.
• A clear bypass pumping plan in their proposal.
• References or documented results, NuFlow publishes many of ours as case studies.
• Familiarity with local regulations and permitting.

If you’re a contractor looking to expand into trenchless rehabilitation, NuFlow offers a path to become part of our contractor network. You can also explore how to become a NuFlow contractor with training, certification, and access to proven epoxy and lining technologies.

For owners and managers, the key is simple: work with specialists who understand both lining design and bypass operations. That’s how you keep your project on budget, on schedule, and out of trouble.

Conclusion

Sewer lining and bypass pumping can seem intimidating, but when you break the process down, it’s really about three things:

1. Keeping flow under control with a well-designed, monitored bypass system.
2. Rehabilitating the pipe from the inside using proven trenchless technologies.
3. Minimizing disruption and risk to your property, your community, and the environment.

When these pieces are planned together, rather than treated as separate problems, you get faster projects, lower total costs, and long-lasting results.

NuFlow has spent decades helping residential, commercial, and municipal clients rehabilitate sewer lines, drain systems, and water pipes without excavation whenever possible. Our epoxy pipe lining and CIPP systems are engineered for 50+ years of service life, and our crews are trained to design and manage reliable bypass solutions.

If you’re facing recurring backups, leaks, or infrastructure concerns, you don’t have to guess your way through it. Share your situation with us and request a free consultation through our plumbing problems page. We’ll help you evaluate whether sewer lining with bypass pumping is the right solution, and how to execute it safely, efficiently, and with as little disruption as possible.

Frequently Asked Questions

What is bypass pumping in the sewer lining process and why is it necessary?

Bypass pumping in the sewer lining process is a temporary system that reroutes wastewater around the pipe segment being rehabilitated. It’s necessary because the host pipe is taken out of service during cleaning, lining, and curing. Without a bypass, flow could back up into buildings or overflow into streets and waterways.

How does the sewer lining process work when bypass pumping is used?

During a sewer lining project with bypass pumping, crews first inspect and clean the pipe, then install and start up the bypass system to carry flow around the work area. Once flow is controlled, they insert and cure the liner (CIPP or epoxy), perform final CCTV inspection, then decommission the bypass and restore the site.

When is a sewer bypass pumping system mandatory during lining work?

Bypass pumping is mandatory when flows cannot be shut off, such as in municipal mains, multi‑unit buildings, hospitals, or critical collectors. It’s also essential when regulations prohibit overflows, there’s no storage capacity, or CIPP curing requires a dry pipe. If you can’t reliably stop or minimize flows, a bypass system must be designed in.

What are the key components of a reliable sewer bypass pumping setup?

A reliable sewer bypass pumping system includes properly sized pumps with solids-handling capability, dependable power and controls, suction hoses or piping in upstream manholes, discharge piping routed safely to downstream points, and valves and check valves for flow control and backflow prevention. It also requires monitoring, alarms, and contingency plans for pump or power failure.

How do contractors size a bypass pumping system for a sewer lining project?

Contractors typically review historical flow data, use short-term flow monitoring, and account for diurnal peaks and potential wet-weather events. Pumps and temporary piping are then sized to handle average and peak flows with a safety factor—often 1.5–2 times expected peak—to avoid backups if conditions change unexpectedly.

How much does sewer lining with bypass pumping typically cost compared to dig-and-replace?

Exact costs vary by pipe size, length, access, and flow conditions, but trenchless sewer lining with bypass pumping is often 30–50% less expensive than full dig-and-replace once pavement, landscaping, and structural restoration are included. Efficient curing methods and good planning can also reduce bypass duration, traffic control needs, and overall project expense.