Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 2/11/2018

When water drains from upstairs washer the downstairs toilet loses a couple inches of water. What could this be?

We live in a 10 year old Townhome. We dont really use downstairs bathroom (water line to toilet is actually off) but im guessing this might have been happening over 6 months or so.
Haven't had any other issues with with upstairs toilets or shower or sinks draining slowly etc. We only lose water in downstairs toilet when water is draining from upstairs washing machine, and every so often when it's happening there will be a plunger sounding noise to go with it. Doesn't happen each time but sometimes.
We had a clog in kitchen sink (that didnt cause any backup in sink) but there was water in basement by kitchen drain pipe. Plumber snaked it to main sewer line other day. Said its good now.

Do you have the same question? Follow this Question

1 Answer


Here is a link to a similar previous question which might help:

The "plunging sound" is likely the water being pulled out of the trap in the downstairs toilet - which then pulls air in behind it, causing a gurgling or chugging sound. Three likely causes - in what I figure is greatest to least likely causes for your case (diagnosing it from probably a couple to few thousand miles away):

1) water in downstairs, unused toilet is evaporating (can go down a half inch to inch or so in a month in relatively normal household humidity) so the trap has very little water covering the outlet hold from the bowl - then when the flushed or washing machine water (high volume flow) goes down the drain stack, it creates a partial vacuum behind it (even if vent pipe is working) and it will pull air from wherever it is easiest. With normal 3-8 inches of water in a trap, the vacuum cannot pull the water out of the trap, so it acts as a barrier to air passing through the trap - that is why it is there (to prevent sewer gases from getting into the house, but works both ways). If the water level in the toilet is low, as the flow reaches the downstairs it is moving fast and pulling a lot of air behind it, so if it can pull air in through the downstairs toilet trap it will do so if it can. Solution might be as simple as using a bucket to fill the downstairs toilet bowl with water every month or two - you should flush a good bit through (maybe with a bit of baking soda or lemon-scented dish soap like Mr Clean (what I use) to sweeten it up so it does not become stagnant so fast.

BTW - be sure to clean that toilet periodically anyway, otherwise you will be hard to remove stains in the bowl. Also, you need to flush water through the tank too or it will go stagnanat and likely go all slimy brown with iron bacteria. Do NOT put a toilet tnk chlorine tablet in - will stop the bacterial growth and going stagnant, but will also rot all the gaskets and seals in the tank and cause leakage because of the high chlorine concentration that will build up. (Does that a bit in normal use, even with the chlorine being flushed out in normal use once to several times a day).

2) if it has been real cold, vent pipe could be frosted solid or near-solid on the roof. Usually, especially with plastic pipes, you will have a buildup of frost around the top opf the pipe which you can see from the ground, but sometimes (especially with metal pipes and/or really cold attic) the moisture in the rising hot sewer gases will frost up and freeze up the vent pipe inside the attic or just above roofline. If this has actually been happening for the past 6 months, unless you live with Santa Claus not likely to be the cause - though birds nesting in the vent pipe can do the same thing.

3) could be the snaked clog went into your main vent pipe (or was at the intersection with the stack and that part did not get cleaned out - that is pretty common place for clogs) and blocked it so the vent stack is not working, so it is pulling air from downstairs toilet instead. If this is the case, I would expect it to happen every time. Running water from a hose down the vent pipe (be sure it is the vent pipe you are in, not a fan vent or furnace or water heater flue or fresh air intake pipe) will usually clear it - rarely it takes a snake run.

Since you said there was water by the kitchen drain pipe in basement (maybe from a floor drain backing up ?) sounds like the blockage you had was in the in-ground (probably under-slab) main sewer line heading to the street - wherethe vertical drain stack in the house turn horizontal to head out under the basement slab to the street is a very common place for clogs and also where the main stack (if you have a full-height independent stack) joins in, so this could well be the case.

Answered 2 years ago by LCD

Related Questions

Terms Of Use
Privacy Policy