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Our caravan has been sitting there for a few months, so I was wondering: how do I clean my caravan fresh water tank?

So I did some research, this is what I found to be the simplest and most effective way:

  1. Empty the water out of your tanks and taps
  2. Add 12.5 mL of 4% household bleach per 100 L of tank capacity
  3. Refill the tanks
  4. Turn on the taps just until the water starts running
  5. Wait at least 24 hours
  6. Flush the tanks and pipes
  7. Refill with fresh water

Want some more detail behind each of the above steps?

1. Empty the water out of your tanks and taps

Before you add in any cleaning products it’s worth emptying the water out of your tanks and taps. There’s two reasons to do this:

  1. Firsly, if the water is contaminated then you’ve removed a lot of the nasties before you’ve even started
  2. By putting in the cleaning product before refilling with water, it guarantees that it’ll be evenly mixed together

If you leave your tanks “empty”, I’d still recommend giving them a flush first. It’s probably worth checking out: Should You Leave Water In Caravan Tanks?

2. Add 12.5 mL of 4% household bleach per 100 L of tank capacity

Bleach is what’s recommended by the authorities to disinfect water tanks

The Department of Health recommends you use 125 mL per 1,000 L of water to disinfect tanks, and the Department of Health and Human Services (Vic) recommends exactly the same thing.

Bleach is both cheap and highly effective as a disinfectant. It kills off bacteria like staphylococcus, streptococcus, E. coli and salmonella. It also kills the flu and common cold viruses.

Bleach is recommended by the authorities to clean water tanks

Yes, you can use other cleaning products… but they do the same job and cost a lot more.

If you have 180 L in tank capacity, the following is what it works out to cost:

  • Household bleach about $0.05 total
  • Milton solution (diluted bleach) about $2.50 in total, and
  • Tank Clean (e.g. Camec) about $15.00 in total

To do exactly the same job.

If you’re thinking of using white vinegar, baking soda… or both? Well, it surprised me to find out that these don’t actually kill off the harmful bacteria.

Read: What Can I Use to Clean My Caravan Water Tank? [Good, Bad, Dangerous]

HINT: Having trouble getting the cleaning solution into the tank… even with a funnel? Pour it into your hose, then connect the hose to the tap. The water will push it through (and it’ll get mixed in thoroughly)

3. Refill the tanks

Fill the tanks up as much as possible. This will make sure that the cleaning solution is in contact with as much of the tank surface as you can.

This will slosh the cleaning product around too, to make sure it’s fully mixed in evenly.

4. Turn on the taps until the water just starts running

Because it’s no good having a lovely clean tank.. to only have the nasty water still sitting in your pipes.

So it’s worth turnining on the taps until the water just starts running, then turn them off. This way you’ve got the tank cleaner doing its job all throughout your caravan’s water system.

It’s probably worth topping up the tank as well now, might as well make sure it’s fully full.

5. Wait at least 24 hours

Depending on what you read the times vary. Some places say 15 minutes, others 6 hours. But the Department of Health and Human Services recommends that after chlorinating, you should wait at least 24 hours before using the water to allow for microorganisms to be destroyed.

Sterilising Caravan Water Tanks - Leave for 24 Hours

I would recommend to err on the side of caution here. If different sources are saying different things… go the longer one! The only thing you’ve lost is a bit of time. Better that then the disinfectant not doing it’s job, and you still getting sick.

HINT: It might even be worth taking your caravan for a drive in this time. There shouldn’t be too much sloshing about if the tanks are completely full… but the reality is there’s likely to be air pockets.

[If you haven’t already, check out Should You Leave Water In Caravan Tanks?]

6. Flush the tanks and pipes

Once you’ve waited the 24 hours, I would dump the water and flush it out. Now, everything I’ve read says that the tanks should be disinfected and the water safe to drink. Unless you’re in a drought affected area where water is like gold, I’d use this as a good opportunity to water the plants.

Emptying the tanks will get rid of any debris or dead germs… and any chlorine taste that may be lingering.

You may even flush it a little more to completely get rid of the taste, but that would be depending on water availability.

7. Refill with fresh water

So now that caravan tanks are clean, it’s time to put fresh water back in. If you haven’t already got one, use the 24 hours you’re waiting as an opportunity to pop down and get an inline water filter.

Leaving Caravan Water Tank Empty or Full - Less Important Than Using an Inline Filter

The best inline water filter is, ironically, the B.E.S.T Inline Water Filter (cheap on eBay)


Cleaning your caravan water tanks can be a pretty cheap and simple process.

I’ll admit: I’ve been fooled in the past by buying stuff like Milton’s and Tank Clean…

But at the end of the day, bleach is what’s recommended by water scientists (and it’s the cheapest option)

You might also be interested inShould You Leave Water In Caravan Tanks?