How can I tell if I have a leak in my pool? Water usage seems high.

[AaronGo]

I will try to make this long story short. I record our water meter the same day the local MUD reads it and it seems like I am using more water than I should be for this time of year in the Houston area. I don't think I have a pool leak but what would be the best way to tell if I do? I turned off the auto-fill at the water spigot to see how quickly water is being lost, regardless of HOW. There should be minimal loss from evaporation since the high temps are 70 (or less) right now. I don't detect any wet spots where there might be a leak in the pool plumbing.

What would you expect loss from evaporation to be around this time of year for an 18,000 gallon pool that has a surface area of ~30' x 15'?

I have our sprinkler system off, so water usage is limited to just household use, which should be fairly low for a family of 4 (which includes 2 kids under 2 years).

Any general ideas to track why our water usage might be higher than expected?

 

[mknauss]

See Pool School - Leak Detection

Your evaporation should be low, but not zero.

Take care.

 

[Texas Splash]

Our pools are close in size, mine 16x40 at just under 18K. My water loss is low this time of year, except it does increase when we have winds. Even with our cooler temps, and my non-heated water at about 56 degrees, wind traveling across the water always seems to speed-up water loss. I haven't watched critically, but if I had to guess I'd say I might lose about 1/4 - 1/2" per week this time of year. It really depends. The TFP Pool School - Leak Detection page has more info. It might help to split leak detection between the suction side then pressure side. Turn-off the pump overnight on a calm evening and watch for drops the next morning. Perhaps have a way to plug some returns if needed to isolate lines and close valves to isolate sections to help you eliminate potential areas of concern. Since plumbing varies between pools, techniques can vary a bit.

 

[AaronGo]

thanks, I will check out the Pool School reference.

The first time I shut off the auto-fill valve the pool went a good 7-10 days before I needed to turn it back on, so my gut feeling is that I DON'T have a leak, but I will do more investigating. And that was when the temps were higher so evap loss would have been more substantial. I would think I could go 2+ weeks without really needing to add water under current weather conditions.

 

[mknauss]

Temperature differential is important (water to air) but wind and relative humidity matters too.

Have you tracked CYA, salt, or CH? If you have a leak they will drop quicker than they should due to water exchange.

Take care.

 

[AaronGo]

So I think I figured out the cause of my issue. I think the auto-fill mechanism is randomly malfunctioning and adding water to the pool when it should not be. My neighbor's and my drains terminate right next to one another at the curb and I was mistaking my drain overflow as his. What threw me off was the randomness of it. It's not like there was water in the street all the time, so I assumed it was sprinkler system runoff since he runs his sprinkler system more than me.

I did turn off the auto-fill at the spigot and water consumption has decreased per my water meter readings, so I am PRETTY sure the mechanism is broken or something is interfering with its operation (maybe the float is sticking). It might be related to the Harvey flooding we experienced or perhaps it's just broken and needs to be replaced.

- - - Updated - - -

BTW, the chems all test fine (no new sharp declines in CYA or CH), so that was the other thing that made me think I don't have a leak.