How to clean a water tank on a (sailing) boat?

Due to lack of circulation, water can become stale and undrinkable. In order to insure safe and clean drinking water on board, your boat’s freshwater system needs to be sanitized if it hasn’t been used for some time, for example before your first use of the system after your boat has been stored for the winter. In order to clean boat water tanks, you have to remove the old water before starting the disinfection procedure.

Here are simple five tips for cleaning your boat’s fresh water tank:

  1. Turn the water pump on and open all taps to drain all of the water out of the storage tank.
  2. Measure 1 teaspoon of household bleach per gallon (of the tank capacity). Pour it inside the tank and immediately add fresh water to the tank until it’s full.
  3. Turn on the water pump and let the bleach water run through all taps for two minutes.
  4. Turn the taps and the water pump off and let the bleach water sit in the tank for 24 hours. When the tank is sterilized, turn the water pump on and drain the water tank by opening all taps.
  5. Fill the water tank with fresh water and drain all water again. Repeat this procedure until the water no longer contains an odour of bleach.

After this procedure your tank should be clean and full of fresh water. The problem is that after a couple of days, this water can already be unsuitable for consumption due to the proliferation of pathogens, like bacteria and viruses. We also strongly discourage drinking water directly from boat water tanks, without using a proper disinfection solution. 


Instead of lugging expensive bottles of drinking water on board, boiling water before you drink it or adding chemicals is order to kill bacteria and viruses, we offer you a UV purification solution that comes with tap- or in-line filter which removes nasty tastes and smells.

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