# Thread: Testing very high chlorine levels > 50 ppm

1. ## Testing very high chlorine levels > 50 ppm

I need to chlorinate my well, and have a TF-50 test kit.

According to people who know things about wells, I need to get 100ppm at the well head.

Can the FAS-DPD test be used for levels this high? If so, any ideas on not wasting reagent.

Thanks.

2. ## Re: Testing very high chlorine levels > 50 ppm

Dilute it in the ratio x:y, (say 5:1) with non chlorinated water and multiply the answer by x+y, (6) ?

3. ## Re: Testing very high chlorine levels > 50 ppm

You should be able to calculate the gallons of water in your well and then simply dose enough using PoolMath to get very close to that target.

4. ## Re: Testing very high chlorine levels > 50 ppm

Originally Posted by duraleigh
You should be able to calculate the gallons of water in your well and then simply dose enough using PoolMath to get very close to that target.
I have done that part already, but for peace of mind I wanted to test the level at the well head.

Can anybody confirm the math for the FAS-DPD test?

Thank you.

5. ## Re: Testing very high chlorine levels > 50 ppm

It can only test that high with dilution of the test. Unfortunately, you lose accuracy this way and a lot of it when you dilute samples for testing FC. I'm not sure why they think you need 100 PPM FC, but that seems excessive to me. Is your well badly contaminated with something?

6. ## Re: Testing very high chlorine levels > 50 ppm

Well tested positive for ecoli and fecal coliform.

Only posting the whole thing because I found it interesting:
15A NCAC 02C .0111 DISINFECTION OF WATER SUPPLY WELLS
(a) Any person constructing, repairing, testing, or performing maintenance, or installing a pump in a
water supply well shall disinfect the well upon completion of construction, repairs, testing,
maintenance, or pump installation.
(b) Any person disinfecting a well shall perform disinfection in accordance with the following
procedures:
(1) Chlorination.
(A) Hypochlorite shall be placed in the well in sufficient quantities to produce a
chlorine residual of at least 100 parts per million (ppm) in the well.
Stabilized chlorine tablets or hypochlorite products containing fungicides,
algaecides, or other disinfectants shall not be used. Chlorine test strips or
other quantitative test methods shall be used to confirm the concentration of
the chlorine residual.
[Note: About three ounces of hypochlorite containing 65 percent to 75
percent available chlorine is needed per 100 gallons of water for at least a 100
ppm chlorine residual. As an example, a well having a diameter of six inches,
has a volume of about 1.5 gallons per foot. If the well has 200 feet of water,
the minimum amount of hypochlorite required would be 9 ounces. (1.5
gallons/foot x 200 feet = 300 gallons at 3 ounces per 100 gallons; 3 ounces x
3 = 9 ounces.)]
(B) The hypochlorite shall be placed in the well by one of the following or
equivalent methods:
(i) Granular hypochlorite may be dropped in the top of the well and
allowed to settle to the bottom; or
(ii) Hypochlorite solutions shall be placed in the bottom of the well by
using a bailer or by pouring the solution through the drill rod, hose, or
pipe placed in the bottom of the well. The solution shall be flushed
out of the drill rod, hose, or pipe by using water or air.
(C) The water in the well shall be agitated or circulated to ensure thorough
dispersion of the chlorine.
(D) The well casing, pump column and any other equipment above the water level
in the well shall be rinsed with the chlorine solution as a part of the
disinfecting process.
(E) The chlorine solution shall stand in the well for a period of at least 24 hours.
(F) The well shall be pumped until there is no detectable total chlorine residual in water pumped from the well before the well is placed in use

7. ## Re: Testing very high chlorine levels > 50 ppm

I don't see why it wouldn't work...yes, you'll lose accuracy if you dilute, but i think your estimate will be plenty precise for your purposes.

How deep is your well, and do you know what kind of formation it's in?

8. ## Re: Testing very high chlorine levels > 50 ppm

505'

6" casing.

Not sure what you mean by formation.

9. ## Re: Testing very high chlorine levels > 50 ppm

He means what the aquifer is composed of. Is it sandy down there or perhaps the water is in a limestone or other rock type formation. Our aquifers here are sandy. Just out of curiosity, what made you have the well tested for coliforms? Was it you who pulled the sample?

10. ## Re: Testing very high chlorine levels > 50 ppm

Granite, I believe.

I just so happen to go to church with a gentleman that works for a local municipality water department, and knew that he would run the tests for me. Water is clear, tastes great, smells fine, but I have small children and didn't get the well inspected when we purchased the house in April so I was curious. He gave me sample bottles, and I pulled the samples myself.

1st sample, removed the screen from the kitchen sink and took the sample, tested positive for Fecal Coliform/ecoli
2nd sample, emoved the screen from the kitchen sink, flamed the tap, and took the sample, tested positive for Fecal Coliform/ecoli

11. ## Re: Testing very high chlorine levels > 50 ppm

I'm not saying you did anything wrong, but it is very easy to contaminate a sample. Sanitize your system and re-test is about all you can do. Go ahead and make sure you have enough reagent since you'll be using a lot. Good luck and let us know how it works out.

12. ## Re: Testing very high chlorine levels > 50 ppm

Here is a great guide for well disinfection put out by the State of Minnesota: http://www.health.state.mn.us/divs/e...sinfection.pdf

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