How to Clean a caravan water tank
Living in Australia, water is a very precious resource and when it comes to caravanning, this is no different. I have spent a lot of time researching the best way to clean a caravan’s or campers water tank and here’s what I have found.
To clean a caravan’s water tank, first drain and flush the system until the water runs clean. Next, fill the tank with a mix of either vinegar or chlorine (see below) and run all the taps for a few minutes. Leave the mix for a few hours before draining and flushing the system again.
To clean a caravan’s water tank, there are a couple of options depending on your situation. A vinegar mix cleans and descales the system well without affecting stainless steel. Alternatively, a chlorine mix is very effective at disinfecting the system but can damage stainless steel.
Why do you need to clean a water tank?
For most of, we simply do not use our caravan water systems frequently enough to keep the water stored in them fresh. Most of the time, we are filling our water tanks from scheme water which is often sanitized with a weak mix of chlorine. The problem is that chlorine dissipates over time and this can allow micro-organisms like bacteria and algae to grow.
Left untreated this can cause you to become quite sick after drinking the water or even using it to brush your teeth. In the worst case, some of these micro-organisms can be deadly particularly for your kids. The most harmful micro-organisms are:
- Cryptosporidium,
- Giardia,
- Campylobacter,
- Salmonella,
- Coli
All of this can be avoided by good water tank hygiene and almost totally eradicated with the addition of a simple filter system (see below).
How often do you need to clean a water tank?
The question everyone asks is how often should you clean your tanks? And as frustrating as the answer is, it totally depends on your situation. For example, if you use your caravan full time and fill your tanks from a chlorinated scheme water point at a caravan park, your cleaning requirement will be far less than someone who only uses their caravan a couple of times a year. The reason being that every time your fill your tank from a chlorinated source, you are dosing the system.
Water testing can be done very easily and cheaply and after doing them a couple times you will get to know what is right for your system.
As a general rule though, cleaning and sanitising your fresh water tank every 3 months or before a trip if more than three months has elapsed in between uses is a good idea. If you have water filters fitted to your system, it’s a good time to change these too.
How do you clean the water tank?
Most caravan water tanks are underneath and are filled from a port in the side of the van. Depending on the tank manufacturer there may also be a an access port which will allow you to get a scrubbing brush inside the tank for thorough cleaning.
For the majority of cases, all that is required to clean the water tank is to
- drain and flush the water tank and system thoroughly (including all the taps and shower).
- Fill the tank will a cleaning solution (see below for options)
- Run all taps and shower again to get the cleaning solution through the plumbing
- Leave the solution to soak for three to four hours (or overnight)
- And then drain and flush the system again until the water is free of taste or odour
- If you have water filters, change these once your system is clean.
The biggest decision you will have to make is whether you use a chlorine mix to sanitise the whole system or use vinegar as a substitute.
There are other options such as bleach (which is actually just a bleach solution but can contain unwanted additives), or lemon juice (which uses the same acidic cleaning principle as vinegar to clean but can be more expensive to purchase). Other options include bicarb or a vinegar bicarb mix but don’t rate highly as they are better suited when the clean required isn’t as deep.
Should you use chlorine or vinegar?
This is the crux of the problem and again comes down to your situation and requirement. First of all, what is the difference between the two solutions and why would you choose one over the other?
Lets talk chlorine first. Chlorine is an alkaline compound that is predominantly used for water sanitation. Just about every pool in the world uses chlorine to kill bacteria and algae that grows in water and keep clean, clear and safe. Fun fact: even salt pools use chlorine (a chemical decomposition by electrolysis of salt which is just sodium chloride into sodium hypochlorite and hypochlorous acid).
The main benefit of using chlorine is that it is very effective at killing a whole range of bacteria that can cause us to become sick if ingested. If mixed in the right quantities, a chlorine solution will kill samlonella, E. choli, giardia, legionella and many algaes very effectively.
The other advantage (and in some respects disadvantage) of chlorine is that it dissaptes into the environment. This means that after a few days the chlorine will have sanitisied your water tank and dissipated leaving nice clean chlorine free water.
The main problem with using chlorine is due to its corrosive nature, particularly for stainless steels. While most caravan water tanks, plumbing and pump components are plastic these days, the sink and water heater components are not. Usually, these components are made of stainless steel. Hence frequent use of strong chlorine mixes can cause problems. Still, its better to replace a sink than it is to get sick!
What about Vinegar?
Vinegar being a mild acid is also relatively effective at cleaning water tanks and can also remove lime scale build up. Vinegar is safe to drink, inexpensive and best of all will not damage stainless steels.
For the most part, vinegar does a reasonably good job at killing algal growths and can kill some bacteria such as salmonella and e. coli however the effectiveness of this solution is not nearly as good as chlorine.
The other disadvantage is that if not rinsed out properly, the water can smell and taste of vinegar until it is flushed from the system.
So in summary, if you are in need of excellent water sanitisation and don’t have a lot of stainless to worry about, use a chlorine mix. If on the other hand your water has been treated regularly and just need a mild clean, use vinegar.
What’s the right ratio when using Chlorine?
If using a liquid sodium hypochlorite solution, mix this in 0.4mL per 10L of water. So an 80L tank would need 3.2mL of 12.5% Sodium Hypochlorite. A 120L tank would need 4.8mL of 12.5% Sodium Hypochlorite. Sodium Hypochlorite can be purchased from hardware stores or pool shops and while you are there, be sure to get the right safety gear recommended like gloves and eye protection.
Just use a small syringe from a chemist to measure out your required dosage. Putting this into the tank before you fill it will help to mix the solution uniformly while filling the tank.
Always double check your dosing measurements and calculations before proceeding.
What is the right ratio when using vinegar?
The best ratio I have found is a one-part vinegar to four parts water mix (ie 20% vinegar). The only problem is that if you have a 100L tank, this needs 20L of vinegar! Other sources suggest anywhere from 5% to 25% as adequate but again it depends on how strong you need this solution to be. The advantage of using vinegar is that it is more of an art than it is a science. Just make sure you are not wasting your money on gourmet vinegar like balsamic!
What about water filters?
If you have water filters make sure you change these after you have flushed the cleaning solution out and only have clean water left. Failing to do this will mean the chlorine or water will be stored in your filters and you will not likely get rid of the taste and odour for some time.
If you don’t have any water filters, consider getting some. These days, cartridge type and reverse osmosis filters are very affordable and easy to install. Best of all, the good systems can even remove heavy metals, bacteria and viruses like giardia and e. coli.
A good system like a three-stage cartridge filter system can be purchased for less than $100 and can literally be a life saver. They are easy to install and maintain and honestly worth the investment even allowing you to get safe drinking water from ordinary bore water. Check out our article on how to select, install and maintain the right system to avoid the common pitfalls of water filtration.
That about wraps it up. If you have any other experiences or suggestions, please leave a comment below.
See you somewhere on our big lap.
Recent Comments