I'm working on an urban project in Tripoli, where water quality is a major concern. Almost all residents are living in 3-8 storey buildings with piped water that is stored in rooftop water tanks. These tanks are never/rarely cleaned, so residents are complaining of sand, algae, etc. It's unclear if water contamination is due to the tanks or the pipes (it may be both).
We're setting up WASH Committees in buildings to maintain shared facilities, and want to come up with a relatively short tank-cleaning procedure that we can train them to perform. The cleaning and disinfection procedures that I've found so far entail lengthy soaking time (anywhere from 6-24 hours), which may deter them from cleaning the tanks regularly. Has anyone found a shorter procedure that is effective and easy/safe enough to teach residents to do themselves?
It would be helpful to know a little more as suggested in some of the other replies. What is the type of water? Are the tanks covered? Have you done any bacteriological tests?
The presence of sand and algae suggests only a problem of material accumulation. Is there any slime growth on the walls of the tanks?
Sediment can be removed by draining down the tank and simply scooping it up before rinsing and refilling the tank. You will need to make sure you don't disturb the sediment during this process. It is worth taking sensible precautions to avoid introducing contamination and use clean equipment, wear gloves etc. The tank could be filled and dosed with a little extra disinfectant to provide a residual to deal with any residual contamination but so the water was still fit for purpose (for example with water purification tablets). If there was any likelihood of faecal contamination (presence of animals or their droppings for example) then a more thorough disinfection would be necessary.
Also, consider what can be done to prevent sediment accumulation. Open tanks will permit algal growth and be exposed to wind blown sand. Keeping them covered, therefore, would be good. What about the water supply; there may also be a source of sediment from carry over from water treatment.
If there is any slime growth, the tank should be drained and the walls and base simply scrubbed clean, rinsed and flushed with clean water before being refilled with water for use. It may be possible to have some control over growth by maintaining a disinfectant residual in the water supply, if one does not exist.
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by Robert Pitchers, WRc plc - Technical Consultant
you have not said anything about source of water -bore well, treated municipal, drawn from lake/pond/river/stream? Some very good solutions have already been offered. As for algae, if the storage is totally prevented from sunlight, algae growth will be minimal.
you have not said anything about source of water -bore well, treated municipal, drawn from lake/pond/river/stream? Some very good solutions have already been offered. As for algae, if the storage is totally prevented from sunlight, algae growth will be minimal.
normally algae growth is hig when your tank is exposed to sunlight, you may protect the tank but if not lets try the regular cleaning and sanitizing process;
1. Prepare a tank, with open top. a hose and a motor pump
2. Calculate the volume of your tank, then make a 1% volume concentration of phosphoric acid
3. Use your tank, fill with water then add the amount of acid to make 1%
4. Pump it up, then by gravity it should go back down to the tank- make it re-circulating for 30 minues only
5. You should see the scales being drained and dissolved by the phosporic acid
6. After a month, repeat the process but use a sodium hypochlorite- make 1% concentration
7. Repeat then the cycle monthly, acid first then next month hypochlorites.
8. No need to rinse too long and too much of the water. The phosporic acid is a food grade, the hypochlorite will simply evolve.
i would recommend a manual processing first to remove all the visuable dirt and as a second step a surface-desinfektion with hydrogen peroxide solution. This requires several technical equipment of the tanks like a drain, two chambers for non-interrupted water-supply and several more. In many cases, cleanings are not done because those responsible have no idea how to handle the process without getting stress. So my recommendation is -> first chance the technical equipment into something workable and then second do the cleaning and desinfection without getting in trouble with the residents.
What is the material of construction of the tank and pipe line. You will have to clean the tanks first manually , then rinse it with KMnO4 with a wet cloth . Wash it with water . Install a on line screen filter . You can repeat chemical cleaning once in six month.
I have attached a file on Guruvani white meant for such public water supply tanks and reservoirs.It will not remove dirt, sedimentation which can be desilted normally. The water will however be fit for drinking purposes,despite such debri remaining in water, including organic bio solids if any as also dissolved solids, nitrates,chemicals, POP heavy metals etc. Sorry for this second post as there was a problem earlier!
We have Vedic Sciences based solutions for tanks and reservoirs of public water supplies to be sanitized and also the water rendered fit for humans, animals and plants use.but not by killing pathogens, algae etc with toxins.I have already uploaded a file which can be accessd at my profile page and I have attached it once again to this reply. We have not yet started helping international clients on large scales but many international visitors have apprecieated these techniques when they visited India and observed Swami Valmiki in action.
Hello, our company Green Erect LLP is having organic liquid solution of your concern. You may clean the tank using BioZYM then disinfect using AqBON. You can have details on our website www.greenerect.com or may write us a formal inquiry at raman@greenerect.com
The issue is that disinfection is a product of disinfectant concentration x time. So you can decrease the time by increasing the concentration. Unfortunately that adds risk that you send water with an excessive disinfectant concentration to the end user's tap.
Your procedure would need to ensure adequate rinsing & no risk that sections of pipe between tank and valve are filled with excessively high disinfectant concentrations, which are then inadequately rinsed out.