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There is an 8000 liter water tank on top of my house which provides water for the house.

Bacteria, fungi, algae, etc often start developing in the tank, giving unpleasant smells, etc.

This chemical seems to be chlorine based. According to the bottle, the composition is:

Sodium hypochlorite 5% max.

Sodium hydroxide 1% max.

Amine oxide 1% max.

I'm thinking of maybe putting 50 ml into the tank about once a week.

Nobody is drinking or cooking with the water. It's used for stuff like laundry, showers, washing dishes, etc.

I know it seems like a strange idea, but I live in the countryside in a developing country and it's not easy to find stuff here.

The water is ground water that we pump up there with our own pump.

What's gonna happen? Should I decrease or increase the amount? Or drop the idea entirely? (And maybe do something else?)

It's very hot here, maybe 40 celsius in the shade. This tank is in the baking sunlight.

Fiksdal
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  • Once a week is maybe too often. You don't use those 8000 l in a week, do you? – Ivan Neretin Jun 02 '16 at 15:28
  • @IvanNeretin Nope, we use maybe 800 liters per day. We top it up maybe once or twice a week. BTW, won't chlorine evaporate into the air gradually? – Fiksdal Jun 02 '16 at 15:31
  • Is your tank sunlight proof ? – ankit7540 Jun 02 '16 at 16:07
  • @ankit7540 Yes, it's made of 10 cm thick concrete and is covered. – Fiksdal Jun 02 '16 at 16:47
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    Could a foam fractionator and ozonation be an alternative for you? – aventurin Jun 02 '16 at 19:38
  • @aventurin Haven't heard of the former. but I have great experiences with the latter for disinfecting vegetables. water for dishwashing, etc. How big of an ozonizer would i need for a 8000 liter tank? – Fiksdal Jun 02 '16 at 21:14
  • I'm not an expert, and its difficult to say since it depends on the amount of biological and chemical material that must be oxidized as well as on the technique used to bring the ozone into the water. Usually this is done by bubbling air that contains ozone through water (therefore the combination with a foam fractionator). The residue of ozone should be less than 0.05 mg/L (50ppb) for drinking water. Also for drinking water bromine and trihalogen methanes might be a problem.

    https://en.wikipedia.org/wiki/Water_chlorination#Ozonation

     – aventurin Jun 05 '16 at 17:52
  • @aventurin Interesting. I have RO, Ozonizer and UV inside the house. I take the water from this tank and run it through it to create drinking water. – Fiksdal Jun 05 '16 at 17:55

1 Answers1

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The product which you have mentioned in your post may have other chemicals like fragrance etc... which may make the water not suitable for washing dishes.  

You can purchase sodium hypochlorite (bleach) which is sold separately as powder or solution and add to the water tank. The concentration added to water tank is crucial.

You can use unscented / fragrance free laundry bleach solution also. This will be easier to find. If you get solution (6% solution of bleach in water) then you can add 40mL to the 8000L full tank first time and mix.

Then, say after a week when your tank has 2400 Liters full (using 800L per day ); you can add 28-30mL again and then fill up tank to full (8000L). (Approximate ratio is 1-1.5mL per 200 Liters of water).

Preventing algal growth:

  1. To prevent the growth of algae it is always recommended to prevent light exposure of stored water. Dark colored/black tanks do well. You can cover the manholes/ crevices through which light may enter the tank.

  2. Additionally, warm water aids in algal growth, so you can try to cover the tank with some tarpaulin etc... to prevent heating.

  3. Regular cleaning is important. Algae already growing on the inner wall of the tank is difficult to to deal with. Proper regular cleaning will help to remove such growth.

ankit7540
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