Adjust Your pH Before Draining?

[HeyEng]

Our local city just put out a reminder that draining chlorinated pool water into the drainage system is illegal. They made a couple of suggestions on how to reduce the chlorine and one "hint" has me stumped. Perhaps one of the chem gurus here might enlighten me. Here is the post:

It’s officially fall, which means pool owners are beginning to close their backyard pools. The City wants to remind residents it is illegal to release chlorinated pool water down storm drains.

Water flowing from neighborhood storm drains isn’t filtered before it drains into local streams and reservoirs.

“Aquatic life cannot tolerate chlorine and other chemicals often found in pool water or backwash water from filtration units,” Environmental Protection Superintendent Derek Johnson said.

However, there are a couple options residents have to safely drain pools. First and foremost, dechlorinate the water before draining. This can be done by allowing the pool water to stand untreated for at least 7-10 days and testing the water’s pH before draining.

 

[JoyfulNoise]

Yeah, that's just dumb. The chlorine in a pool will be completely depleted as soon as it hits the storm drain from all of the organic matter it will contact. I suppose any chloramines created could be harmful but their concentrations will be low. It's not like every pool owner in the area is going to drain their pools at the exact same time ...

As for pH, no idea why that would matter for chlorine. I suppose people do crazy things with their pool water and then dump the toxic stew of chemicals down the drain. So having water with pH that's off the charts in either direction probably isn't all that unexpected.

I have drained my pool many times into my front yard (it's a large area of my property that no one uses or sees because of how my home is oriented to the neighborhood. The birds absolutely love it when I drain water and the ground in that area always blooms with a thick patch of weeds every time ... so yeah, my toxic pool water is super-bad for the environment