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7 Easy Steps to Sanitize Your RV Water Tank

7 Easy Steps to Sanitize Your RV Water Tank

Making sure to sanitize your RV water tank is one of the most crucial items of any regular RV maintenance routine. A clean water tank will make your travel so much better. You’ll always have clean, fresh-tasting water for drinking, cooking, and even bathing and doing dishes.

Unfortunately, many RVers don’t get around to cleaning their tanks until their water starts tasting strange or comes out cloudy. At this point, cleaning it becomes more of an emergency than a regular maintenance item.

If you’re not familiar with how to sanitize your RV water tank or if it seems too complicated, read on. We break down the process in simple steps and explain how easy it is. Here we go! 

Items Needed to Sanitize Your RV Water Tank

The good news is you don’t need any specialty items to sanitize your RV fresh water tank. All you need is a large pitcher, a measuring cup, and a gallon of plain liquid bleach. Don’t use bleach with any added fragrances or any other special ingredients.

You could use a special detergent or formula specifically made for sanitizing your fresh water tank, but it’s really not necessary. These simple ingredients are all it takes. 

How To Sanitize an RV Water System

How Often Should You Sanitize RV Water Tanks?

Most experts recommend you sanitize your RV water tanks at least twice a year. Of course, if your freshwater smells or tastes strange, you’ll want to sanitize it right away. 

If you’re taking your RV out of storage after an extended period, it’s a good idea to sanitize your water tank then too. You never know what kinds of bacteria might grow while your RV is closed up.

How to Calculate Amount of Bleach Needed for Your Water Tank

You need 1 ounce of bleach per 8 gallons of water in your fresh water tank. (Or ¼ cup of bleach for every 16 gallons of water.) To determine how many ounces of bleach you need, divide your total tank capacity by eight. If your tank holds 40 gallons of water, you’ll need 5 ounces of bleach (40 ÷ 8 = 5).

NOTE: Whatever the final amount of bleach, you must dilute it in at least 1 gallon of water before adding it to the water in your fresh water tank.

Pro Tip: Never Add Undiluted Bleach to Your RV Plumbing System

Never add undiluted bleach directly to your water tank or RV water system. It can damage seals, gaskets, and fittings in the plumbing. 

Adding undiluted bleach to your RV plumbing can cause damage.

Understanding the different components of your RV water system is key to proper maintenance. Learn more here: How Does an RV Water System Work?

Use the calculation we provided above to determine how much bleach you’ll need to sanitize your fresh water system based on its capacity. Then, add that bleach in a diluted solution to your full fresh water tank per the instructions below.

7 Easy Steps to Sanitize Your RV Water Tank

We’ve warned you about using the proper amount of bleach AND diluting it before putting it in your RV’s fresh water tank. So now, let’s go over the seven simple steps to sanitize your RV water tank. 

1. Turn Off Water Heater and Drain All Fresh Water

You never want your water heater to be running when you sanitize your RV water tank. Turn it off and drain it first. Leaving the water heater on while cleaning your tank will damage it.

Also, let the water cool and leave the water pump on before draining the heater. This will help to get all the water out. 

RV water heater switch
Turn your water heater off before sanitizing your fresh water tank.

2. Bypass Your RV Water Heater

Bypass your RV’s water heater by closing the valves that allow water to flow into and out of the water heater. Yes, it’s that simple.

If you have an icemaker, shut that off and close the valve to it.

If you have an onboard water filter, bypass it as well. This probably won’t be as simple as closing valves, as there’s typically plumbing beyond the water filter that you’ll want to sanitize. If your rig doesn’t have a bypass built-in, remove the water filter and attach a piece of flexible tubing between the connectors.

3. Add Diluted Bleach Mixture to RV Fresh Water Tank

Fill your fresh water tank to between a third and a half of its capacity. For example, you should use 20 to 25 gallons of water for a 50-gallon tank. After adding the water, pour in the diluted bleach mixture per the calculation we provided earlier. 

Simple Trick for Filling your Freshwater tank when Boondocking - Tips from Tom

4. Fill Fresh Water Tank with Fresh Water

After putting water in the tank and adding the diluted bleach mixture, fill your fresh water tank to capacity. It should be completely full so that the sanitizing solution can reach all the nooks and crannies in your fresh water system.

5. Open Every Faucet One at a Time and Run It Until You Smell Bleach

Once the tank is full, open all the faucets in your rig one at a time until you smell bleach. This is how you know that the sanitizing solution has made its way through all the pipes to the various fresh-water fixtures.

6. Let Sanitizing Mixture Sit for Several Hours

Bleach is a powerful sanitizing agent, but it can also cause damage when you use it at full strength. That’s why we dilute it first.

But diluting it also slows its effect on bacteria in the system. Once the solution spreads throughout your fresh water system, let it sit for several hours, so the bleach can do its magic.

Class C on the road
Taking your RV for a drive can help slosh around the diluted bleach, ensuring your fresh water system gets thoroughly cleaned.

If possible, take your rig for a short drive before letting it sit for a few hours. Driving around for a couple of miles can slosh the sanitizing mixture around to help ensure that as much of the fresh water system as possible gets treatment.

7. Drain Your Fresh Water Tank and Flush the System with Fresh Water

After letting the sanitizing mixture sit for six to eight hours, completely drain the fresh water tank from your low-point drain. The low-point drain is typically near one end of the fresh water tank.

Once the tank is empty, refill it with fresh water. Run your faucets one at a time until you no longer smell bleach. If you drain the tank but still smell bleach, repeat the process until the bleach smell disappears. 

Then, refill the fresh water tank and return your water heater, ice maker, water filter, and other appliances to normal operation.

RV kitchen sink
After draining and refilling your fresh tank with clean water, run your faucets until you no longer smell bleach.

Regular Sanitization Keeps Drinking Water Safe and Clean

Now you know how easy it is to sanitize your RV water tank. It probably seems like a lot at first, but after doing it a time or two, you’ll see it’s relatively simple. And it’s well worth the effort.

Not only does it make your fresh water safe for drinking, it also keeps it tasting fresh. Clean, safe water is better for cooking, doing dishes, and showering, too.

Still not convinced your fresh water is safe? Here’s everything you need to know: Is It Dangerous to Drink from Your RV Fresh Water Tank?

Additionally, sanitization goes a long way towards being more environmentally friendly. When you can drink from your fresh water tank, there’s less need to purchase bottled water, which creates a lot of excess trash. Avoiding bottled water can also save you quite a bit of money.

Make sanitizing your RV water tank a regular part of your routine – at least twice a year – and you’ll reap the rewards in your health and comfort.

Fresh Water
It’s safe to drink water from a sanitized fresh water tank.

Your black tank requires regular cleaning too. However, you don’t want to use bleach for this task. Read What RV Toilet Chemicals Should You Use? to learn more.

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Dalton Bourne

Sunday 27th of March 2022

Using bleach to disinfect water tanks is not new to every RV, but how much bleach is needed to disinfect an RV water tank. We need to know the exact amount to kill pathogens and keep them at a safe level. In general, we will need one cup of bleach for every 50 gallons of water. Therefore, if your water tank has a capacity of 25 gallons, use ½ cup bleach. If your water tank can hold 12-13 gallons of water, use 1/4 cup.

Glen Taylor

Tuesday 18th of January 2022

Simple steps to clean your RV tankL Drain, mix solution. Add solution. Fill it up and let the solution work. Remove bleach.

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