Testing after rain - waiting period, or no?


Well-known member
Sep 23, 2009
I'm just wondering if I'll have inaccurate results if I test my water too soon after a rainfall. Yes, I always take my samples from an arm's length depth, so not to test the water that's "on top". I just have a feeling that I'm flying through my first TF-100 kit since opening the pool, and I don't want to waste any of it if I can help it. Thanks for any help.


Mod Squad
TFP Expert
Platinum Supporter
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In The Industry
Apr 1, 2007
Sebring, Florida
If your pool was in balance prior to the rain, it will still probably be so.

Unless the rainwater from the decking runs into your pool istead of away from it, there will be little change

You can test for your self anytime but you would get the most accurate results If your pump was running at least an hour after the rain so your water was thoroughly mixed.

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