Sewer backup protection · Boulder, CO
Backwater Valve Installation in Boulder, CO
A backwater valve is a one-way valve on the main sewer line that lets wastewater leave the house and closes when sewage tries to flow back in. It protects basement floor drains, showers and toilets when the public sewer surcharges during heavy rain or a blockage downstream. B&D Plumbing installs backwater valves in Boulder homes where the layout and code allow it.
How Does a Backwater Valve Work?
A backwater valve works with a hinged flap that stays open while sewage flows out of the house and swings shut when flow reverses. The valve body sits inline in the building sewer, usually in the basement floor near where the line leaves the house, with a removable cover for cleaning.
When the city sewer backs up, the pressure that would push sewage up through your floor drain closes the flap instead. While the flap is closed, wastewater from your own fixtures cannot leave either. During a backup event, keep water use to a minimum until the flap reopens.
Who Needs a Backwater Valve in Boulder?
A backwater valve makes the most sense for homes with basement fixtures that sit low relative to the street sewer, homes that have had sewer backups before, and homes in low-lying areas near creeks.
- Finished basements with a bathroom, laundry or floor drain, where a backup would ruin finishes
- Previous backups that came from the street side, not a clog in your own line
- Low-lying lots along creek corridors
- Code-driven cases: the International Plumbing Code calls for backwater protection on fixtures whose flood-level rims sit below the elevation of the next upstream manhole cover in the public sewer
A home that backs up because of roots or a broken pipe in its own line needs sewer line repair first. A backwater valve does not fix a blockage on the house side.
Boulder Sewer Backups and Who Pays for Protection
In Boulder, a backwater valve on your sewer line is the homeowner's project, because the City of Boulder places responsibility for the sewer service line on the property owner, up to and including the connection to the city main. We found no City of Boulder backwater valve rebate program, so plan on it as a private improvement.
Boulder has seen why the protection matters. During the September 2013 flood, sewer backups into basements were a widespread problem across the city as the system filled with stormwater. Homes along Fourmile Canyon Creek and Wonderland Creek in creek-side North Boulder sit in the drainages that carried that water. Check your homeowners policy for sewer backup coverage at the same time. Many standard policies exclude it without an endorsement.
What Does Backwater Valve Installation Involve?
- Camera inspection. Confirm the line's route, depth, material and condition, and make sure the valve goes into sound pipe.
- Choose the location. The valve must protect the low fixtures without blocking upstairs fixtures that should drain freely. It goes where it can be reached for maintenance.
- Cut the slab. A section of basement floor is saw-cut and broken out over the line.
- Install the valve. The plumber cuts the sewer pipe, sets the valve level and in the correct flow direction, and connects it with proper couplings.
- Add an access box. A riser and cover bring access up to floor level for cleaning.
- Inspect and test. Where a permit is required, the installation is inspected before the floor is patched. Water is run to confirm the flap opens and seats.
- Patch the floor with concrete.
What Affects the Cost of a Backwater Valve?
Backwater valve cost depends on where the line runs, how deep it sits, what the floor is finished with, and the condition of the pipe at the install point.
- Floor finish: bare concrete versus tile, carpet or finished flooring over the line
- Depth of the sewer line below the slab
- Pipe condition: old cast iron or clay at the install point may need a section replaced
- Interior versus exterior installation, depending on layout
- Permit and inspection where required
How Do You Maintain a Backwater Valve?
To maintain a backwater valve, open the access cover at least once a year, remove any debris from the flap and seat, and confirm the flap swings freely. Paper, grease and wipes can hold the flap partly open, which defeats the purpose. Keep the access cover visible and unobstructed, and do not cover it with flooring.
What If Sewage Is Coming Up Now?
If sewage is backing up into the basement right now, the job is cleanup and clearing the line, and the valve comes after. Stop using water, keep people away from the area, and call for an emergency plumber in Boulder. Once the cause is known, a backwater valve can be planned so it does not happen again. B&D Plumbing handles the full range of Boulder plumbing repairs, from the emergency through the fix.
Backwater Valve Questions
Is a backwater valve the same as a backflow preventer?
No. A backwater valve stops sewage from flowing back into the house through the sewer line. A backflow preventer protects the drinking water supply from contamination, for example on an irrigation system.
Does Boulder require a backwater valve?
It depends on the installation. Plumbing code calls for backwater protection where fixtures sit below the next upstream manhole cover in the public sewer. For existing homes, adding one is usually a choice, and the plumber checks what applies to your layout.
Can I use my basement plumbing while the valve is closed?
No, not without risk. While the flap is closed, water from your own fixtures cannot leave the house and collects in the line. Limit water use until the backup clears.
Will a backwater valve stop all basement water?
No. It stops sewage coming back through the sewer line. Groundwater coming through walls or floors is a drainage and sump pump problem.
Had a Sewer Backup Before?
Call B&D Plumbing at (720) 571-0891. We inspect your sewer line and tell you whether a backwater valve makes sense for your basement.
Licensed plumber · Answered 24/7 · 2525 Frontier Ave, Boulder