A sewer backup starts either in the utility's sewer main or in the house drain, and the answer decides who clears the blockage. Water that rises at the lowest drain first, or at several houses at once, points toward the main. A backup at one fixture that clears when the cleanout is opened points to the house drain.
Key takeaways
- Anchorage Water and Wastewater Utility runs the wastewater service for Anchorage, Chugiak-Eagle River, Peters Creek, Eklutna and Girdwood.
- The house drain is the owner's to clear through a plumber, and the utility's main is the utility's to clear on its own line.
- Sewage is treated as contaminated from the first minute, so keep everyone and every pet out of the water until the crew has confirmed it is safe.
- Stop using every drain and toilet until the blockage is cleared, because each use adds to the water in the system.
- A backwater valve, where one is fitted and maintained, stops water from the main coming back into the house.
What is the difference between the main and the house drain?
The utility's sewer main is the pipe under the street that carries wastewater from many houses, and the house drain is the pipe that carries the wastewater from one house to the main. The utility owns the main, and the owner is responsible for the house drain up to the point where it joins the main.
The point where the house drain meets the main, and any cleanout on the drain, is the usual dividing point. The arrangement for a particular property can vary, so the boundary for your address is for the utility to confirm on its own line.
A backup is a sign that the flow has stopped somewhere between the house and the main. The question is where that stoppage sits, because the answer decides who needs to act and how quickly.
A short diagram of the drain, the cleanout and the street connection, drawn from the plumber's or the utility's information, makes the boundary easier to explain to anyone who has to act on it. Keep a copy with the house records, because it shortens the next call.
How can I tell which one is blocked?
Look at which fixtures back up and in what order. A backup that rises at the lowest drain in the house first, or at several houses at once, points toward the main. A backup at one fixture that clears when the cleanout is opened points to the house drain.
Note the drain that backed up, the room it is in, whether it is the lowest point in the house and whether other drains are affected. A toilet that gurgles when another fixture is used, and a shower that drains slowly, can both point to a blockage in the house drain.
Open the cleanout only if it is safe to do so, and only with protective equipment. Do not open it while water is under pressure, because sewage can spray. A plumber or the crew should open it. A plumber can usually tell from the cleanout and the line which side of it the blockage sits on, and that is the answer to give the utility or to keep for the record.
Look also at whether the water rises in other fixtures when the first one is used. A backup that clears and then returns when a washer drains suggests a partial blockage that the washer's flow is pushing against. Writing down which fixture was used at the time helps the plumber narrow the search.
Who clears a blockage on each side?
A blockage on the house side is cleared by a plumber, and the owner pays for it. A blockage in the utility's main is the utility's to clear, and the owner calls the utility on its own line and gives it the time and the drain that backed up.
Ask the plumber for a written scope and for the credentials the job requires before any work is done. A plumber will usually clear the house drain with equipment, and will say whether the drain needs a repair or a replacement.
Tell the utility which drain backed up, when it happened and whether other houses in the area are affected. The utility can then decide whether to send a crew to its main. Keep the utility's answer with the record of the backup.
Where a backup affects several houses on the same street at once, it is more likely to be in the main, and the owner should call the utility before paying for work on the house side. The utility can say whether it has a report from its own system, and that information decides which party should be doing the clearing.
How is sewage cleaned up differently from clean water?
Sewage contains bacteria and viruses, so it is treated as contaminated from the first minute. Porous materials that have been in contact with it, such as carpet, pad and the lower part of drywall, are usually removed rather than dried, and hard surfaces are cleaned and disinfected with products suited to that category.
The crew wears protective equipment for the work and explains which materials are removed and why. Clothing, bedding and soft goods that have been in contact with sewage are usually discarded, because they cannot be disinfected to a reliable standard.
Hard, non-porous items can usually be cleaned and kept. The crew tells you which items fall into which group, and the owner keeps a list and photographs of each item before it is removed, for the insurer.
What should I do before the crew arrives?
Keep everyone and every pet out of the water, stop using the drains and toilets, close the room, and call the line. Do not use a household vacuum or a fan on sewage, and wash your hands if you touch the water.
Tell the line which drain backed up, which room the water is in, whether it is clean or grey or dark, how far it has risen and whether it is still coming up. Those facts let the crew send the right equipment and the right person.
Do not use a drain or a washer in the house until the crew says the drains are clear. Each use adds water to the system and can bring sewage back up, and a single flush can make the backup worse.
Keep a record of who cleared the drain, what equipment was used and what the plumber found, with the date. If the backup returns, that record is the first thing a plumber or the utility will ask for, and it tells them where to look next.
What if the backup comes back?
A backup that comes back after cleaning means the blockage was not cleared or the cause has not been fixed. A root in the line, a partial blockage in the house drain or a surcharge in the main will bring the water back, so the cleanup should wait until the cause has been dealt with.
The crew checks the drain before it dries the room and runs the drain to confirm the water flows away. A drain that backs up again after cleaning should be checked by a plumber, and the utility should be asked to look at its main if the blockage is in the street.
A backwater valve, where fitted and maintained, stops water coming back into the house from the main. Ask a plumber to check whether a valve is fitted, where it sits and whether its flap moves freely.
How do I keep a backup from happening again?
Keep fats, grease, wipes and sanitary products out of the drains, have the house drain inspected if the house is old or the drain is slow, and ask a plumber to check any backwater valve. Note whether backups follow heavy rain, because that points to a surcharge in the main.
A plumber can scope the house drain with a camera to show the condition of the pipe, the joints and any roots. A camera survey is a clear record, and it tells you whether the drain needs cleaning, repair or replacement.
Keep a note of any backup, with the date, the weather and the drain involved. That record helps the plumber and the utility spot a pattern, and it shows an insurer when the backup happened and what was done.
Frequently asked questions
Who pays for clearing a backup?
The owner pays for a blockage on the house side through a plumber. The utility clears its own main. Whether an insurance policy pays for the cleanup depends on the policy and any backup endorsement, and the insurer decides.
Can I clear the blockage with a drain snake myself?
A homeowner can try a simple drain snake on a house drain, but a sewage backup should be handled by a plumber, and the cleanup must be done with protective equipment. Do not force a snake into a cleanout under pressure.
Is it safe to use the toilet after a backup?
Not until the drain has been confirmed clear. Using the toilet adds water to the system and can bring sewage back up into the room. The crew tells you when the drains can be used again.
Why did the backup happen during heavy rain?
Heavy rain can push water into the sewer system faster than it can be carried away, and the water can rise in the lowest drains. A backwater valve is designed to stop that water coming into the house, and the crew records whether one was fitted.
Should I call the utility or the restoration line first?
Call the restoration line first if sewage is in the house, so the room is made safe and cleaned. Then call the utility about its main, and ask a plumber to look at the house drain. Give each caller the same facts.
What does the utility need to know?
The utility needs the address, the drain that backed up, the time it happened and whether other houses in the area are affected. Ask it to confirm in writing what it has found and what it will do about its side.
How long does it take to clear a blockage?
It depends on where the blockage is and what is causing it. A simple blockage in the house drain may clear in a single visit, while a root or a collapsed section of pipe takes longer. A plumber or the utility will say what it expects once it has seen the line.
Will the utility come out if the blockage is in the street?
The utility repairs and clears its own main. Call the utility on its own line, give the address and the drain that backed up, and ask it to confirm whether it will send a crew and when it expects to act.
This guide is general information for Anchorage Municipality homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.