Cleaning Caravan Water Tanks

💧 Cleaning Caravan Water Tanks – 7 Easy Steps!

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Over time, caravan water tanks can become hotspots for the build-up of algae, mould and other harmful bacteria. This can be caused by the combination of different water qualities being added to the tank, as well as other environmental factors such as heat and stagnancy.

Cleaning caravan water tanks is a maintenance task that should be performed periodically to ensure the best quality drinking water while caravanning.

In addition, if the water tastes a bit funny, or you think people may have become sick due to a dodgy water source, it’s best to give the tanks a full clean.

First up is selecting the best product for cleaning your caravan tanks, then follow the step-by-step instructions below.

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Which Product Should You Use for Cleaning Caravan Water Tanks?

Caravan Sink
Having clean drinking water is essential

Firstly, you’ll need to decide which product you’re going to use to clean your caravan water tanks.

In short, plain household bleach is the only one that’s 99.9% effective and works out to cost only $0.05 per 200 litres of water.

To draw your own conclusion, below is the run-down of using…

  • Bleach
  • Vinegar
  • Milton
  • RV Tank Cleaners
  • Bicarb Soda

Cleaning Caravan Water Tanks with Bleach

Regular household bleach is the cheapest and most effective product for cleaning caravan water tanks as it has powerful disinfectant qualities, killing 99.9% of bacteria and germs.

According to National Library of Medicine:

“Bleach is a strong and effective disinfectant – its active ingredient sodium hypochlorite is effective in killing bacteria, fungi and viruses, including the influenza virus. Diluted household bleach disinfects within 10–60 minutes of contact time.”

Bleach kills the following bacteria & viruses:

  • Influenza virus
  • Common cold
  • Staphylococcus (causing staph infections)
  • Streptococcus (causing strep throat)
  • Salmonella (causing diarrhea, fever, and stomach cramps)

What Bleach to Use for Cleaning Caravan Water Tanks

Any plain household bleach, which can be found in supermarkets and hardware stores will do the job.

Make sure the bleach you buy has at least 4% available chlorine (sodium hypochlorite) and has no additives, fragrances or detergents.

How Much Bleach to Add to the Caravan Water Tanks

The dilution ratio is 6.25 mL of bleach per 50 litres of water in your caravan tanks.

6.25 mL (bleach) : 50 litres (water)

Use the following table to work out how much bleach to add based on the total volume of your water tank/s, which can also be found at Health.vic.

Tank Volume (L)Bleach Qty (mL)
50 L6.25 mL
100 L12.50 mL
150 L18.75 mL
200 L25.00 mL
250 L31.25 mL
300 L37.50 mL
350 L43.75 mL
400 L50.00 mL
450 L56.25 mL
500 L62.50 mL

Cost of Cleaning Caravan Water Tanks with Bleach

The cheapest bottle of unscented bleach at Coles and Woolworths is the 2.5L bottle of White King Standard Bleach, costing $4.80 AUD.

To clean 200 L of caravan water tank capacity, you would need 25 mL of bleach, costing a tiny $0.05.

Cost to clean 200 L water tanks with Bleach: $0.05 AUD

Cleaning Caravan Water Tanks with Vinegar

White vinegar is often touted as the natural cleaner of the ages and while it does make a great surface cleaner, it’s not a good disinfectant.

Vinegar will only kill or reduce certain pathogens, including:

  • Escherichia coli (E. coli)
  • Salmonella
  • Listeria monocytogenes
White Vinegar

According to the EPA, for a product to be considered a proper disinfectant, it should be able to kill 99.9% of harmful germs within 5 to 10 minutes.

Difference between cleaners & disinfectants according to Healthline:

  • Cleaners – physically remove surface dirt, debris & some germs
  • Disinfectants – destroy or inactivate 99.9% of harmful germs (including viruses and bacteria) within 5 – 10 minutes

Because of this, vinegar can never be classified as a disinfectant and should only be used to clean caravan water tanks if it’s an emergency and you can’t get your hands on some bleach.

How Much Vinegar to Add to Caravan Water Tanks

The general ratio for cleaning with white vinegar is 1:1, which means equal parts water to equal parts vinegar.

In other words, if you want to clean a 200 L water tank, you would need 100 L of water mixed with 100 L of vinegar.

That’s a lot of vinegar!

Hence, cleaning caravan water tanks with vinegar is not a viable solution in addition to the fact that it won’t kill all of the germs.

Cost to clean 200 L water tanks with Vinegar: $85 AUD

Cleaning Caravan Water Tanks with Milton

Milton Sterilising Fluid is nothing more than diluted bleach, containing only 2% sodium hypochlorite.

On the other hand, regular household bleach contains about 5% sodium hypochlorite, which is what’s required for a proper caravan water tank clean.

Milton Sterilising Fluid
Milton Sterilising Fluid →

How Much Milton to Add to Caravan Water Tanks

The following dilution ratios can be found on the Milton website.

Dilution Ratios for Milton Products:

  • Milton Sterilisation Fluid – 90 mL per 5 L of water
  • Milton Sterilisation Tablets – 3 tablets per 5 L of water
Tank Volume (L)Milton Liquid (L)Milton Tablets
50 L0.9 L30 tablets
100 L1.8 L60 tablets
150 L2.7 L90 tablets
200 L3.6 L120 tablets

Cost of Cleaning Caravan Water Tanks with Milton

A 500 mL bottle of Milton Sterilising Fluid is about $11 at the supermarket or you can get a 30-pack of tablets for $10.50

Using the above ratios, you’d need about 7 bottles to clean 200 Litres worth of caravan tanks, which would set you back $77.

However, when chatting to other caravanners who’ve used Milton for cleaning their water tanks, most people just use one bottle for all of their tanks.

Given that Milton is a watered-down version of bleach, you’re not likely to have as good a clean with Milton as you would with bleach.

Cost to clean 200 L water tanks with Milton: $77 AUD

Cleaning Caravan Water Tanks with RV Tank Cleaners

There are also a range of RV water tank cleaners on the market, which some caravanners swear by.

Walex Commando Drop-ins (tank cleaner)
Commando Drop-ins →
(Caravan RV Camping)

How Much RV Tank Cleaner to Add to Caravan Water Tanks

Each product will vary, with dilution instructions listed on the label.

As an example, a 200g container of Coast Tank Cleanse Pro will clean up to 200 L of water.

Cost of Cleaning Caravan Water Tanks with RV Tank Cleaners

Again, each product will vary in price. Below are some examples.

Cost to clean 200 L water tanks with RV Tank Cleaners: $24 – $44 AUD

Cleaning Caravan Water Tanks with Bicarb Soda

While baking soda will help to dissolve organic compounds like dirt and grease, it’s ineffective against most bacteria.

In essence, baking soda is not a disinfectant, therefore it will not do much in the way of cleaning your caravan water tanks.

If you were going to get in there and scrub your tanks with a brush, bicarb soda would work well to clean the surface with a bit of elbow grease. But, since the inside of caravan tanks are inaccessible, it’s better to rely on bleach to do the job.

Cleaning caravan water tanks with bicarb soda: Not Recommended

Cleaning Product Summary

To summarise all of the above information, here’s the verdict on how each cleaning solution rates when it comes to cleaning caravan water tanks.

(per 200 L)
Bleach99.9% Effective & cheap$0.05
VinegarOkay to use in a pinch, but won’t kill all germs & bacteria$85
MiltonDiluted version of bleach – not as effective$77
RV Tank CleanerEffective & convenient, but pricey$24 – $44
Bicard SodaNot recommended
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How to Clean Caravan Water Tanks

Emptying Caravan Water Tanks
Emptying caravan water tank from the bung

Now that you’ve chosen your preferred product, follow the steps below for how to clean the caravan water tanks.

Empty the Tanks & Water Lines

The first step is to completely empty whatever water is already sitting in the caravan water tanks and water lines. Use the liquid gold to water the ground or gardens rather than waste it, if possible.

Reasons to Pre-empty the Tanks:

  • Eliminates any contaminated water
  • Helps to mix the cleaning product evenly once water is added

If your caravan water tanks have been stored empty for a period of time, it’s helpful to give them a flush before adding any cleaning product.

Is it Best to Store Water Tanks FULL or EMPTY? →

How to Empty Water Tanks & Water Lines:

  1. Open the water tank bung/s underneath the caravan
  2. Turn on all of the taps (including the shower) inside and outside the caravan until they run empty

Add Cleaning Solution to the Tanks

Now it’s time to add your cleaning product into the caravan water tanks. Either use the dilution ratios stated above or read the label (for RV tank cleaning products).

  • Adding pods or tablets – just drop them in via the water tank fill-hole
  • Adding liquid (e.g. bleach or Milton) – use a funnel to help pour it in, or put the liquid into the end of your hose and let it drain in that way

Refill the Tanks with Water

Now fill up all of your water tanks to the fullest capacity possible.

As the water is added, the cleaning solution will mix around and make contact with most of the water tanks interior surfaces.

There is always a little air pocket at the top that never fully fills up, but hopefully, as the water is being added and sloshing around, it will hit the top surface as well.

If you have trouble filling your water tanks (e.g. the water keeps spurting out, rather than filling up), check out the troubleshooting tips below.

Water Tank Filling Issues (Troubleshooting) →

Turn on the Taps to Fill the Water Lines

Outdoor Tap
Don’t forget outdoor taps

To make sure that the cleaning solution is also doing its job in the water lines throughout the caravan, turn on each tap (one by one) until water starts to run out, then switch them back off.

Repeat this process with all taps (internal and external), including the shower, to ensure that all water lines have been filled with the cleaning solution.

You will then need to top the tanks back up to replace the water you’ve just used in the taps and lines.

Leave for 24 Hours

Health.vic recommends letting the solution stand for 24 hours to allow all germs and bacteria to be destroyed.

Some sources say that you can do it earlier, but longer is better in this case, just to be sure that all of the bad stuff has been killed off. It won’t harm your tanks to leave it longer.

You can take the caravan for a drive around the block if you want to really mix up the solution and make sure all inside surfaces have been covered.

Empty & Flush the Tanks

After you’ve left the solution for 24 hours (or a little longer), it’s time to empty all of the water out of your tanks and water lines.

Repeat the same initial process by releasing the bung underneath the caravan and/ or letting it flow through your taps and out the grey water hose onto the garden.

After the tanks are completely empty, turn all of the taps on until they also run empty.

It’s a good idea to refill the water tanks and empty them again if you have enough water supply to do so. This will help to rid the tanks of any leftover bleach taste. However, it will still be fine to drink if you can’t.

Refill the Water Tanks for Use

Inline Water Filter
Refilling the caravan water tanks using an inline filter

Now you’re free to refill the water tanks for regular use.

Using an inline filter while travelling is a good idea, which easily attaches to your hose as you’re filling up your tanks. This gives an extra level of protection against nasties in the various town waters you’ll be drinking.

The Stand At Ease Water Tank Filler (above) helps to fill your tanks much easier and means that you don’t have to stand there holding the hose in the exact position the entire time.

That’s it! Now your caravan water tanks should be nice a clean, ready for your next trip.

Where to Find Water on the Road →
Caravan Maintenance & Service Log

Caravan Maintenance & Service Log

Log and track all of your caravan maintenance and servicing requirements.

  • 7-page Planner (digital & printable)
  • Caravan Service History Log
  • TICK OFF checklists
  • COMPLETE maintenance tasks
  • ADD in extra tasks
  • RECORD maintenance & service dates
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