A practical guide to sanitizing your RV water system

Sanitizing the water system and fresh water tank is a task that intimidates a lot of RV owners. Especially newbies. The truth is, it’s pretty easy to do and it doesn’t require any special equipment. Once you do it a few times, you’ll feel like a pro. 

This guide walks you through the steps of sanitizing the system, and answers a few common, general questions about the fresh water tank and water system.

If you prefer, you can download a PDF version of this guide.

Here's the sanitization process in a nutshell:

1. Dilute a bit of bleach with water
2. Add the chlorinated water to the fresh water tank through the water filler
3. Run the water pump to distribute the chlorinated water to all parts of the plumbing system
4. Let it sit for a few hours
5. Drain the chlorinated water out
6. Re-fill the fresh water tank and flush the plumbing

That’s it. 

Honestly, the only (sort of) complicated part of the procedure is calculating the amount of bleach and working with a diluted bleach solution.

This guide breaks down the steps in a bit more detail and walks you through the procedure.

THINGS YOU NEED FOR THIS PROJECT

• Your Airstream Owner’s Manual
• Household bleach. Use plain unscented household chlorine bleach with at least 5% sodium hypochlorite, found in supermarkets 
• A metal or glass measuring cup (don’t use plastic)
• 1 gallon jug of water, about 80% filled with water
• A flexible funnel, like the yellow one shown below – you can find these at Amazon by searching for "flexible funnel"
• Rubber gloves (optional but recommended)   
• Calculator

 TIPS

• Wear old clothes and shoes – to keep possible splashes of bleach from ruining them. 
• Wear rubber gloves – to keep possible splashes of bleach off your hands.

STEP-BY-STEP PROCEDURE

PREPARATION: Before starting this procedure, make sure your gray water holding tank has been dumped. Also, if you have a water filter, remove it or bypass it before following the sanitization steps below.  

1. Add the capacity of your fresh water tank to the capacity of your water heater 

You’ll find the fresh water tank capacity in your Owner’s Manual. 

If you have a water heater with a tank, it usually holds 6 gallons. 

If your Airstream has a tankless water heater you can count it as zero gallons. By “tankless,” we’re referring to various water heaters that lack a large tank, such as the Girard GSWH-2 used in most aluminum Airstream trailers since 2021, Alde Compact (used in Classics), Truma Combi (used in Basecamp 16/16X and Interstate 19), Suburban Nautilus IW60 (Basecamp 20/20X), and Timberline (used in Rangeline motorhomes).

The fresh water tank in our Globetrotter 23FB holds 30 gallons and the water heater holds 6. That makes our total water system capacity 36 gallons. 

2. Multiply the total capacity by 0.13 to determine the amount of bleach you’ll need to use, in ounces 

Using the example above, here’s the math: 36 gallons x 0.13 = 4.68 ounces.

This means we use 4.68 ounces of bleach to sanitize the system. 

3. Measure the bleach and pour it into the gallon jug of water that you’ve filled to 80% full

This dilutes the bleach, making it easier to pour. 

If you want to keep possible splashes of bleach off your hands, wear rubber gloves.

4. Use the flexible funnel to pour the chlorinated water into the fresh water fill

Use the funnel so you don’t drip or splatter bleach water on your clothes or your skin. 

If some bleach gets on the Airstream it won't hurt it immediately, but it’s best to rinse it off with plain water anyway.

5. After you’ve dumped the contents of the entire jug into the system, fill the remaining capacity of the fresh water tank with clean water

Use your regular hose, connected to city water. Now your fresh water tank is filled with chlorinated water, which will kill bacteria.

6. Let the entire contents of the tank flow through the water system

To do this:

• Disconnect the city water hose

• Turn OFF the water heater

• Turn ON the water pump

• Turn on all of the faucets and water outlets, one faucet at a time

Run the first faucet on full hot and keep the water flowing for 3 minutes or until you can smell bleach – which indicates the chlorinated water has made it all the way through the water heater and hot water line.

If your water heater has a tank, it may take the full 3 minutes before the chlorinated water is noticeable at the first faucet. This is because most of the 6 gallons of water in the water heater has to be displaced first.

Next switch the faucet to cold for 1-2 minutes. It doesn’t take as long for the chlorinated water to run through the cold water line, since there’s no water heater in the way.

Then move onto the next faucet and run the hot and cold sides for 1 minute each.

Complete this process for all faucets, toilet, shower, and outside shower if you have one.

7. Let the diluted bleach solution sit in the system for at least 4 hours 

This is the minimum amount of time to sanitize the system. Leaving it longer will not hurt anything, so don't worry if you have to let the diluted bleach solution sit until the next day. 

8. After the sitting period, drain all the water from the fresh water tank

Open the kitchen and bathroom sink faucets fully (midway between hot and cold), turn on the water pump, and fully open all the faucets. This will take a while, perhaps 10-20 minutes depending on the size of the fresh water tank. 

Turn off the faucets when the water starts to sputter (indicating that the fresh water tank is nearly empty). Now the chlorinated water is in the gray water holding tank.

OPTIONAL

To ensure all of the chlorinated water is out of the plumbing, you can open the kitchen faucet fully, and also open the low-point drain petcocks on the bottom of the fresh water tank. The residual water in the plumbing lines will drain out onto the ground. However, be aware that the runoff of the chlorinated water on the ground might affect plants nearby. 

9. Refill the tank with fresh water and dump the gray tank

Refill the fresh water tank with water. At this point sanitizing is done. However, there may be a residual smell of bleach in the plumbing system. Optionally, you can repeat Step 9 to flush the plumbing more thoroughly.

Whether you flush the system once or twice, there may be a slight lingering odor of bleach for a while, but the water will be safe to use.

Dump the gray tank as you normally would.

TIPS AND TRICKS

To keep the fresh water plumbing as clean as possible, get a good external water filter and use it every time you hook up to campground water or fill the tank.

If you're bothered by a chlorine smell after flushing the system, rinse the system with a solution of 1 quart of vinegar to 5 gallons of water. While you are refilling the tank in step 10, dump it in. Then flush the water out again until there is nothing left in the tank. Refill the tank with fresh water.

There are also commercial products to make the water taste better, which you can find in RV stores and camping stores.

If next time you want the sanitizing process to go faster, double the bleach ratio (to 0.26 x your water tank capacity) and you will only need to let the water sit in the system for 1 hour.

3 COMMON QUESTIONS

“Is it safe to drink the water from the tank?”

We get this question regularly and the answer is yes – as long as you regularly sanitize the system. 

If you want to be absolutely sure about drinking water quality from the fresh water tank, you can also investigate under-sink filtration systems that are rated to filter down to 0.2 microns, and/or use UV light to disinfect the water. But the important thing is to regularly sanitize the plumbing.

“Will bleach damage the lines or fittings in an RV water system?”

If measured and used correctly, the bleach concentrations recommended for sanitizing will not hurt any part of your plumbing system. 

Understand that sanitizing the system is not “bleaching” the system. It’s chlorinating the water and disinfecting the plumbing. The concentration is a bit stronger than in the chlorinated city water you have in your home, but not strong enough to do any damage.

Dealers and others who try to convince you that bleach will damage the water system and rubber fittings are usually trying to sell you a product that is a bleach alternative. You may choose to use one of these products to avoid working with bleach, but be aware that the cost is typically much higher.

“We never drink the water from the tank so why should we sanitize?” 

If you don’t, bacteria can multiply inside the lines of the entire system, and that is never good. 

Remember, even when you’re hooked up to campground water you’re using the same plumbing lines in the Airstream.

Even if you only drink bottled water, at some point you’re going to use the tank water for cooking, brushing teeth, showering, washing dishes, or perhaps the dog’s water bowl. For all these reasons, sanitizing is important.

Download this guide as a PDF