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Marc, Plumber
Category: Plumbing
Satisfied Customers: 1595
Experience:  Plumbing heating & home maintenance contractor
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Todd, We added a full bathroom daughters. The bathroom

Customer Question

Hi Todd, We added a full bathroom for our daughters. The bathroom was/is in empty attic space above our garage, as is their bedroom.
Our problem is when the sink is not used for several days a horrible smell is present. After we run faucet water from the sink, the smell goes away.
Why is this and what can we do to fix it?
All of the plumbing in this small bathroom works fine... toilet, shower and sink.
Submitted: 2 years ago.
Category: Plumbing
Expert:  Marc replied 2 years ago.
Hello and thank you for your question. I will assist you today to the best of my ability.
Expert:  Marc replied 2 years ago.
This smell that you are experiencing is not uncommon after many days of non use. It is caused because the water is evaporating or being siphoned out of the trap under the sink.
Expert:  Marc replied 2 years ago.
When water evaporates from the trap, it opens up the trapway allowing sewer gases and the odor to enter through the drain piping into the home. When you run the water, it fills the trapway back up and seals any gases from entering.There are a couple of things that can be done to prevent this from happening. 1) Install a trap primer, which will add small amounts of water to the trap every time a faucet is used elsewhere in the home. This would be a bit costly and unsightful but the most automatic and practical way to rectify the problem. 2) go to the sink ever couple of days and run the water3) let the faucet drip very slightly so there is a constant flow of water into the trap. this is probably the cheapest, easiest fix for a faucet/bathroom that does not get used often.