I had a contractor add an additional bath. When we were planning out the project, he mentioned my lack of a water heater valve drain pan. Instead, he installed a drain directly into the septic line that runs from the new bathroom (toilet/sinks/tub) out to my main septic line. Is this actually safe? There’s no trap as far as I’m aware. Anytime the bathroom is used, there’s a significant smell. It isn’t rotten eggs, but it’s still concerning

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  • 7
    "Anytime the bathroom is used" are you speaking literally or euphamistically.
    – Jasen
    Aug 27, 2022 at 8:57
  • 4
    I find it curious that you claim it doesn't smell like hydrogen sulfide. I've had the displeasure of dealing with two septic fields, and both of them were unmistakably smelly. Are you sure it isn't a French drain? They can be stinky under the right conditions.
    – J D
    Aug 28, 2022 at 14:18
  • 1
    I can't really see what I'm looking at in that tiny photo. Did you bother to ask whether there's a trap? Maybe you're getting everyone in a lather over nothing.
    – isherwood
    Aug 29, 2022 at 18:11

3 Answers 3


NO NO NO. It's not safe. Your plumber was completely incompetent or negligent to do that. It definitely needs a trap. I would make him fix it.

  • Is there anyway I can self check for a trap there or is it even possible to install one in the middle of a septic line? Aug 27, 2022 at 3:36
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    Before you sue him have the local code people inspect it and ask them for a written report if it is wrong. He did get a permit didn't he? If you cannot do that get an independent contractor to take a look at it. That way when you go to court you have documentation from a qualified third party.
    – Gil
    Aug 27, 2022 at 6:20
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    @AustinSeward - You can check for a trap by running a camera down the drain.
    – Hot Licks
    Aug 27, 2022 at 20:58
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    And instead of sueing him, you could also explain your findings and "ask" him to repair it in a very timely manner. You can always ramp up your methods, but maybe start with a simple one.
    – Martijn
    Aug 29, 2022 at 7:39

There may be a trap but if no water was put in it won't stop the smells. Contractors sometimes forget to add water to floor drains. The water will also eventually evaporate from the trap if there is no regular source of water flowing down the drain. Add water to drain and see if smell goes away.


A water heater drain should never drain to a septic tank.

One purpose of the drain is to reduce or eliminate water damage to your home in case the tank leaks. However, if the tank develops a fast leak and your septic tank absorbs it, if unnoticed for just a few hours, your septic field could be irreparably damaged.

A water heater drain should be installed like a sump pump / foundation drain -- it should direct the water outside onto the ground or to a municipal storm drain. It should not go to a sewer or septic system.

  • 2
    I upvoted because this job is obviously a bad hack, but I was curious what the rationale is for the claim that a leak can irreparably damage a septic field. What are the long-term problems?
    – J D
    Aug 28, 2022 at 14:09
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    @JD it's not a long-term problem; it can happen fast. If water flows into your septic tank too quickly it can overflow and carry unprocessed solids and sludge into the leech field. If the laterals & soils in the field get fouled, there may be no way to repair it without also replacing the dirt or relocating the leech field to a secondary site. Both are costly. This is why households on septic should have a septic tank alarm if they do a lot of laundry on one day, or otherwise have bursts of water use. Aug 28, 2022 at 17:52
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    @JeffWheeler There are lots of different designs of septic systems. Only the crudest ones would send unprocessed solids into the leech field (AKA septic field in other parts of the country). Even for a gravity fed system, a well designed system has 3 chambers: The first is for collecting the solids, then a filter to the second chamber to contain the solids, then the third chamber is a pump chamber (if not gravity fed) that only feeds filtered effluent to the septic field (leech field). Not only that even if a leech field gets saturated, just not using it for several month will heal it. Aug 29, 2022 at 4:56
  • @GeorgeAnderson however "just not using it for several months" isn't necessarily a practical solution for everyone.
    – barbecue
    Aug 30, 2022 at 14:09
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    @barbecue Agreed. My only point was that it's not a lost cause if the septic field gets overwhelmed . Aug 30, 2022 at 14:35

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