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S01 E22 - How to Sanitize your Freshwater System
Words and photos by Perry Mack
‘Sanitize’ is a term that is now commonly used every day as killing viruses and bacteria is more important than ever. While winterizing and de-winterizing are other familiar terms among experienced RVers, sanitizing the freshwater tank often is overlooked.
Like a stagnant summer pond grows algae and hatches mosquitos, the stale, wet confines of a freshwater tank can be a breeding ground for bacteria, protozoa, algae and mould. When you take your RV out of storage, we suggest you take time to sanitize your tank.
By not having clean drinking water, the chances of illness increase. Many enthusiasts use inline water filters and while they’ll remove sediment, chlorine, and some heavy metals, they often won’t prevent microorganisms from getting in. Serious contamination is easier than you may think. It only takes a careless moment by someone at the dump station to contaminate the freshwater fill hose or you could fill your tank somewhere before the boil water advisory becomes public.
How often you should sanitize your tank depends on how often you use your RV. As a rule of thumb, it should be done every six months. If you don’t use it very often, it’s recommended you perform it every three months. A partially full tank that sits unused makes a great breeding ground. We sanitize our tank before and after storage (if we store it!)
It's a relatively simple process to sanitize your freshwater tank. You can always get a professional to do it, but if you have some time, a funnel, some household bleach, and a measuring cup, you can easily do it yourself.
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RVs are configured differently, but they all have a freshwater tank drain. This is the valve on our Black Rock 22RKS travel trailer.
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You should also have low-point hot and cold water drains for the pipes. These are the ones in the convenience centre of our Montana High Country fifth wheel.
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Many low-point drains like the one in our travel trailer are located under the RV at the rear.
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The Black Rock has an easy-to-use and access-gravity feed. However, for the High Country, we needed to attach a threaded hose fitting to our funnel to pour in the bleach mixture. Make sure you have the valve set to ‘Fill’.
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Don’t forget to switch the single-handle residential-style faucets to both hot and cold while filling pipes with a bleach solution and then flushing them after.
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After soak-sanitizing the system overnight, drain your freshwater tank and then fill it with fresh potable water. Use your water pump (not a city water connection) and open all the faucets to pump the freshwater through your water system until you can’t smell (or taste) bleach. You may have to repeat this step more than once.
Step 1
Turn off the water heater and then drain the water system. Open the low-point water drains (both hot and cold), your freshwater tank drain, and the hot water tank drain (yes, some organisms love to grow there as well). We turn on our water pump to get out as much water as possible, as quickly as possible. Just be careful not to let the pump run dry as it could cause damage.
Step 2
Measure 60 ml (¼ cup) of bleach for every 55 L (15 gal) that your tank holds and pour it into a bucket with 4 L (1 gal) of water. Our Black Rock 22RKS has a 290 L (77 gal) tank so we add 1.25 L (.3 gal) of bleach to 4 L (1 gal) of water. Pour this diluted mixture into your freshwater fill with the help of a funnel (or water pump if you have one).
Step 3
Fill the freshwater tank with clean, potable water. By filling it to the top, you’ll know the whole tank is getting sanitized. Now, turn on all of the faucets one at a time until you smell the bleach water coming out. Close each one after you do.
Step 4
It takes some time to work properly and we suggest you leave it for five to 12 hours. We leave it overnight. Then drain the system and refill the tank with clean potable water. Open all of the faucets once again, flushing the system until you can’t smell (or taste) bleach. You may have to repeat this process a couple of times.
Step 5
Replace any water filters and you’re done!