Friday, September 22, 2023


Why filter perfectly good water?

By Greg Illes
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. 



  1. We installed a water softener in our class A with the clear housing filter in front of it to reduce the contaminants entering the softener. Our unit has a factory filter installed but I wanted a clear housing one before the softener. Works great and I don’t worry about the California P65 cancer warning. Used correctly there is no problem, these filters have been around for decades.

  2. We use a Camco filter at campgrounds. I always run the water a few seconds before hooking up. But we only drink bottled water when traveling. Although the risk is low, suffering for a day or two with diarrhea from bad water while on vacation ………. no thanks. But we shower and wash with it. Also, each Spring, I flush out the system with tap water from our house and bleach, and rinsed again. When we start out, we carry our own water in case the campground water is nasty. Happy Trails.

  3. I choose simplicity and low cost for water treatment.

    I use the Camco water filter when filling the tank. Carbon filter. Price is reasonable. Lasts many months.

    I use specified amount of bleach for the gallons of water I put in tank, or Camco TastePure Water Freshner, which is sodium hypochlorite (which is bleach). Camco bottle is fragrance free, properly diluted and $5. If I recall a 16 oz bottle treats more than 400 gallons.

    I don’t leave city water hooked up to RV, as I don’t want to have a pipe burst and then deal with cleanup. Using tank allows me to treat water easily, inexpensively, and be assured it’s filtered and growth free, without complex products.

  4. I have been using the Camco blue filter for almost three years. I had read some reviews recently on the Clear20 filter. It filters to 1 micron as opposed to 20 microns for the Camco. A couple weeks ago I needed to purchase a replacement filter. The Walmart had the Clear20 filters in stock so I decided to try it. There is a noticeable improvement in the taste of the water. The Clear20 is about twice the cost of the Camco, but worth it for me to have cleaner water. A filter usually last me six months, so the cost isn’t significant.

    I would be interested in trying the system mentioned in this article, but I can’t figure out which filter the author is using. I visited the Pentek website but it was not helpful. They have so many different types of filters.

    • Amazon sells all of the filters mentioned. I use a three filter setup. Two large filters to filter water into my water tank. One particle and the other carbon block. The last one is connected to the water line coming to the sink faucet on the cold side. Its a Doulton Ceramic Sterasyl (Imperial). That is for only using the water for cooking and drinking. The Doulton filter works well because you can take it out and clean it. The particle filter can also be cleaned. The carbon block filter cannot be cleaned. I also don’t use campground water hookups. I filter all of my water directly from a hose into my water tank. Continual use of the water tank water keeps it being refreshed all of the time. A couple of times a year I’ll drain the water tank and disinfect it with bleach and have had no problems. I do not trust water from a campground from a faucet. Not worth the gamble!!

  5. All – His choice for a clear housing is excellent idea. I put one of those in my wish list on amazon. However, it would have been nice if he listed specific part number for the items so there was no guess work on our part.

    Here is what I do now. This is especially true in AZ, TX, and FL or way south in any of the gulf states close to the ocean. We have filter housing on the outside of the water system-between hose bib and incoming hose to caoch, which pre filters water coming into coach. Built into Coach is another filter housing which we also use. We only use FW tank and not often direct use of city water. In states mentioned above we purchase bottled water to cook with. We filter any tap water we use with a counter top filter, so in effect all water we might cook with or drink is filtered three times, even the bottle water. I sanitize the water system at least once a year, unless it’s been sitting for longer than 4 months, then I do it again, before use. Water Sanitization can be found online. You can also buy PUROGENE products which they talk about. Do web search, better than the bleach solution.

    We got sick from bad water once, it will not happen again ever, I am {bleeped} about keeping system clean. I take Lysol wipe and clean hose bib in all RV parks down for 30 seconds minimum (saw dog owner let his pet pee on one and that cured me from accepting them to be clean). I am clean nut about water. I also clean bib once we leave, even though you should also clean them before use, especially today.

    With present situation, coach has not been used in 2 months, and will be another 1 months before it goes anyplace, so first stop going to sanitize system using the purogene method, It’s full of RV antifreeze now so has to be cleaned.

  6. Years ago on our first trip to Quartzsite, we filled up with water in town at the Pit Stop – several times. On the way home, the toilet started having flushing issues. The poorly designed unit had a spray ‘thingie’ on the back which started not spraying properly. I called the toilet mfg and they were useless. We managed ok, but when we got home I called our RV repair guy and explained the issue. His first comment was, “So, how long were you in Arizona?”. This, before I even told him we were IN Arizona! Apparently, Arizona is famous for high calcium water, which filters do not filter out. Ours certainly didn’t. It was caked on the sprayer in our toilet.

    Fast forward about a year, and we bought a new toilet that can handle Arizona water, and continue to use our one-filter clear canister system and a Brita. The Pit Stop sells reverse osmosis water, but unless you’ve won the lottery recently, you can’t afford to fill up with it. As another reader mentioned, the reverse osmosis system wastes more water than it produces, so when boondocking this is out of the question.

    As an aside, we rarely hook up to water in campsites. We fill our onboard tank and work off of that.

  7. I use the blue 5 micron filter with a 1 micron filter after it going through a softener to the trailer. I always test for hardness and have usually found it very high. This has worked well for me. Got home from a few months in the southwest four weeks ago. I also drink water right from the tap in the trailer. No problems.

  8. I use the “On-The-Go” water softener. I noticed adding all that carry water before (tank located in back of TT) and a bike in the back added trailer sway. Decided the places we go to I can fill water there and eliminate the transportation weight too. Softener provides a great shower. We bring reverse-osmosis water for cooking and drinking.

  9. No in-RV filter, so we run a “blue” filter, you know the kind large camco, on the hose to city water connection, then to drink we filter everything through zero-water filters, works great.

  10. The author must have been looking over my shoulder. Just removed my winter hose & filter setup then put a fresh whole house filter in service. My biggest water problem is calcium buildup. Those screen washers are the best solution (short of a full softener unit) for my limited wet bay space.

  11. Our setup is pretty simple. We use the standard 5 micron blue inline to keep out the boulders from coming through. Then the water goes through a .5 micron whole house filter before it goes into our tank. For drinking we use and absolutely love our Berkey. It does a great job and no matter where we fill up from it always tastes the same and is crystal clear. We sanitize the fresh water tank and lines twice a year with bleach also. It works for us.

  12. We started out with those disposable in-line filters, but I quickly realized they didn’t have the ability to do much, so I built a two canister filtration system. The first filter is a 1-micron particulate cartridge, and the second is a 5-micron charcoal filter. A 3-ft. hose connects the pressure regulator [adjustable and gauged] and filters to the spigot, then a second hose brings the filtered water into the coach. After 16 years, no plumbing problems of any kind, and the water is odorless and debris-free. Filters replaced every three months.

  13. In the RV, we use bottled water for cooking and drinking. Traveling with pets, we do not need an upset animal from “bad” water. Park water is okay for bathing and flushing. So far, so good.

  14. We also have a pentek system with 0.5um filtration. An addition is a brita pitcher in the fridge for drinking and cooking water. I am pretty fussy about the taste of water and this set up has worked for us going on 4 years now. We change the filter about every months but sometimes sooner when we’re doing more off the beaten path traveling. Now if only treating hard water was this easy 😉

    • I use a “On the Go” water softener. It’s quite affordable, I only have to recharge it about every 3 months. It uses non iodized table salt, one container. We don’t carry or use bottled water. We’re fulltimers, we fill our water tank before we leave the campground, always traveling with a full water tank. I’m adding one more filter as Greg suggested, prior to the softener. I have a whole house filter already.

  15. Some contaminants can be colorless and tasteless. Activated charcoal takes many of these chemicals away. The most complete cleaning comes from reverse osmosis. In that system the water is forced to go through a semi-permeable membrane which only allows pure water to pass under pressure.

    Drinking contaminated water may not have immediate noticeable effects on your health, but if you want the best, filter your water.

    • My issue with reverse osmosis is the amount of waste water. If I remember correctly it takes 2-3 gals of water to make 1 gal of RO water, the rest goes down the drain or into the grey tank. We have a 2 cartridge set up for whole house (our 5th wheel) and a Berkey for drinking/cooking water. It works for me, not only saves water but eliminates a lot of plastic bottles.


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