Radon in water mystery This is 30 year old data is from 10 wells in Maine measured over 3 weeks showing a variability of about 1/2 to double over 3 weeks. Of course this is Maine.
Your results are a lot greater. Getting a precise water sample takes a precise method for sure. In my last research I used a hose connection at the indoor well tank faucet routed into a 5 gallon bucket. I set volume low on the hose and when the there was enough water in the bottom of the bucket I placed hose into the sample vial under water and then capped it under water. Then repeated with a second vial. I got good precision between the two samples. But you said you also had good duplicate precision so that would indicate your method is good.
1 3,090 1,420 117%
2 21,200 12,400 71%
3 43,600 24,900 75%
4 66,400 18,900 251%
5 85,000 69,238 23%
6 99,200 40,781 143%
7 125,000 95,549 31%
8 128,000 107,196 19%
9 164,000 125,603 31%
10 1,080,000 758,760 42%