Is it necessary to filter my water?

Is it necessary to filter my water?

By Greg Illes

Most – if not all – RVs come with a water filter installed, usually under the sink where it filters all the water running out of the faucet. But that raises the question, why filter perfectly good water? The answer to that question is another question: How good is “perfectly good”?

Many RVers use the water that the RV park supplies, straight from the tap. After all, that water comes from treated sources and should have no problems. Right?

Well – maybe. Yes, it’s reasonable to assume that a typical chlorinated municipal supply is biologically safe. But that’s only guaranteed at the water treatment plant output. The distribution system can be full of flaws that degrade the quality of the water before actual use.

And that’s not to mention if the local water is coming from a private well, with something subtle in the treatment protocol not working properly. UV irradiation bulbs burn out, filters get clogged, etc.

Aside from health issues, rust and sediment are the biggest culprits, and they increase with the age of the distribution system. The photo shows a graphic example: a new ceramic 0.5um (micrometer) filter, and a second one with only a few hundred gallons through it. It was so clogged with rusty sediment that the flow had slowed to a trickle. It had never been used anywhere except from certified sources.

Odors and tastes can be “safe” but still objectionable. A friend’s house, in another town, provided municipal water with a noticeable “stink” when it first came out of the faucet. Nobody got sick, but it wasn’t pleasant.

Bottom Line: When I fill my motorhome’s fresh water tank, I would like to be certain that the next 75 gallons of water I drink, shower with, or use for cooking, is going to be good for my equipment, and good for me.

But such certainty is a real challenge. I can’t possibly test for contaminants and parasites every time I need a fill. And I can’t have every single possible filtration and treatment protocol (there are dozens) applied to all the water I take on.

The answer, as with so many things in life, is a compromise. With properly treated water as a baseline, I have settled for a simple configuration: a fairly fine-pore sediment filter augmented with activated carbon. The fine-pore filter removes all but the tiniest particles of sediment and screens out any nasty protozoans that might have crept in (e.g., giardia, cryptosporidium). The carbon takes out any odors and tastes. For me, this is an acceptable balance between trouble/cost and quality/safety.

In order to keep an eye on my filter’s health, I chose a clear whole-house housing like the Pentek 150071 (shown). The business of actually doing the filtration is handled by a special high-flow cartridge like the Pentek Flo-Plus, which has great flow performance even with fine (0.5um) filtration. I would hate to have great water at the cost of an hour’s wait to fill my tank. (Not to mention holding up the people in line behind me.)

I screwed pipe-to-hose adapters into the housing so that it could be connected right at the source faucet – that way, I don’t let any “strange” water into my hoses or fittings.

YMMV (“Your mileage may vary,” for those who don’t know) – Note that different people (preferences, allergies, etc.), different water, locales, and use demand different solutions. What works for me might not be your best or safest choice. I’ve only outlined my configuration here by way of example, and not as advice. I’ve seen people with dual-filter setups, UV-light setups, silver-impregnated cartridges – the list goes on. Some folks don’t bother with filtration at all. Some people boil every drop that they drink. It’s up to each individual to sort out their own best approach.

Please feel free to leave a Comment about your own “adventures” with water, and your own filter solutions. We can all benefit (and often be entertained) by each others’ experiences.

Happy travels, and safe and healthy living as well.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his excellent blog at .



8 thoughts on “Is it necessary to filter my water?

  1. Roger Marble

    Sorry, Neither of my Coachmen Class-C RVs (2008 & 2016) came with any water filter under any sink.

    I use CAMCO filter for every drop of water going into my RV, even when filling tanks at my home.

  2. Scott Taylor

    I opt to use a spun sediment filter 1st, then a ceramic cartridge filter.. Worst water issues we experienced were in Newfoundland – MANY parks had “boil orders” posted for their water systems, since they depend on many surface water sources

  3. George

    As I’ve travelled in over 30 states, no doubt there are various issues possible. I installed a separate water pressure system dedicated just to drinking water. I use the 5 gallon water jugs (one in use and one on standby). Correct, there is no guarantee of water purity but I’m not drinking out of my fresh water tank that harbors god knows what since the last time I sanitized it.

  4. Captn John

    I fill the FW tank with 60 gallons before leaving on every trip. An external filter is used. An external filter is used at every CG. We use bottled water for drinking and cooking. I have bypassed every internal filter provided by a manufacturer. They are the weakest link in every RV water system.

  5. Irv

    Based on the number of external filters that I see in campgrounds, most RVs don’t Have internal filters. Maybe most of the monster rigs…

  6. Firechief019

    We have been full timing for 4 years throughout the US. The Big Blue cannisters hold a large filter to allow maximum flow and minimal filter changes. After the water leaves our pressure reducer it flows into the first cannisters equipped with a Pentek dual density poly cartridge. The cartridge has a prefilter of 50 microns and a secondary filter at 5 microns. This takes care of the large particles. Then it flows into a 16,000 grain water softener. This minimizes hard water deposits in our water heater, clothes washer, dishwasher and provides good suds for cleaning. After the softener the next Big Blue has a Pentek 0.5 microns Carbon Block filter for fine sediment, taste and odors. I change filters about every 3 months. Have not run into a park where we could not bring the treated water out of the tap.

  7. Robbie

    Filters used:

  8. Jeff

    All the water going into my 5th Wheel is filtered. I use 2 different filters, A Camco External Hose Filter and a Drinking water filter in the Refrigerator, that also works for the ICE maker as well.

    When I fill my fresh water tank for use on the road, I use my external water filter to fill that tank.

    Both of these filters are Activated Carbon Filters and give clean fresh tasting water.

    The water around the country varies greatly. Some places have high IRON content. In one case in a Houston RV park, the water provided by the park was so full of crap, that it actually plugged up my external water filter. I’m glad that happened, because I would not want all that Crap in my RV water system.

    Those RVers who don’t use a water filter and just hook up to the RV park water supply should reconsider. Some Water systems, whether from a Well or City Water can be highly contaminated with chemicals, and just general dirt and garbage.

    Also, each and every time you hook up, you should flush your hose for at least a minute to make sure the water is clear. Some RV parks have old piping systems, (Iron Pipes) and you can expect allot of rust to come out.

    Bacteria issues always present a problem in some cases as well.

    Depending on how long we will be out on the road, we usually carry at least 2 cases of Fresh Bottled Water, just in case!

    Just some thoughts.

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