I have attached an image of the "well" (for lack of a better description) in my pool house. I have asked two different pool companies what it is and neither one knew.
We moved into this house with the existing pool 5 years ago. The well has never overflowed until this year. (Like much of the country we are really soggy.) I have hung a pump over the well to keep it from overflowing. (I pumped all the water out first - and it just fills right back up.)
We were afraid if we just let it overflow and sit it might damage the concrete foundation of the pool house. Also it doesn't continue rising to flood the yard it stops at a certain point.
The water is coming from our city water, I know this because our water bill last month was $198 and this month it is $245!
Someone please tell me what this thing is and it's purpose and how to fix it so I don't have to take out a loan to pay the water bill.

Just a dumb electrician here, so just guessing, I am thinking it is intended to be a dry well to drain the pool pump/filter. To confirm it is related to your city water, perhaps you can shut off the water at the main valve, for a day if possible, to see if the well still fills up.

While your city water is on, does the meter still run when you know you have every sink, spigot, and hose shut off? Observing this will help confirm water usage that is running up the bill. I know some utilities have the meter inside, while some have the meter out in the yard or at the street. With the meter inside it is easy to check usage, and any leak will be noticeable.

I can imagine a meter in the ground out at the street is much more difficult to check, and there can be a leak in the underground piping that is not noticeable, running up the bill , and allowing water into the ground, and could contribute to the water rising in the "well".

Real mystery you have. Perhaps if you copy your question to the plumbing forum, reword the heading a bit to get someone's attention that your question is not just about pool equipment , you may get a better answer.

Hi there,

I think I can provide at least some advice on this situation.

This sump tank is the collection point for your water sanitation system. It was installed in your pool room because where you live there is a building code requirement that does not allow release of chlorinated water into your water table. The water when you backwash your pool is piped into the tank where it is tied in with your houses sanitation line with a gravity fed system.

The sump tank overflowing is either from a crushed or drainage line somewhere in your system. This can happen in wet areas where ground saturation causes compaction and can crush and flatten your drainage lines.

Given that you have a unexplained water bill, I believe that the sump is overflowing from a broken or unmonitored water supply. Your pump and filter look to be about 15 years old so I imagine a pool related problem seems likely. If you have an automatic water leveler I would definitely check this first. It would be in your deck maybe near your skimmer alongside the pool edge. It has a float valve like a toilet and does require periodic maintenance or repair. It has a pressurized fresh water supply line which could break if let on during freezing temperatures.

Its hard to say for sure what the problem is except to say that it sounds pretty serious and should attended to ASAP.

Steve Goodale
Serendipity Pools & Artificial Rock