Drinking water filter…

Over the years of being on the road in my RV, I’ve run into the occasional unpleasant water situation. City water or well water that didn’t meet my expectations regarding purity, smell, and flavor. To counter that, I’ve bought a few filters over the years that attach to the RV park’s faucet preceding my hose. Often finding it difficult to attach to the strange piping I’d find at older or out of the way RV parks. Having this Camco Water filter on hand is all well and good, but sometimes, I’m just too tired to bother, the weather is awful, the park’s water spigot is deep inside a water box below the ground’s surface so the filter won’t fit, or many other reasons. I’ve had to replace a couple because of cracks due to excess strain on the plastic when I tighten it too aggressively to a water spigot to get it to stop dripping, or strained it into too small a water box and it would leak. As a result of those problems, often as not, the filter doesn’t get connected. Just sitting in my wet bay doesn’t do much good, so when I bought this newer RV, I was happy to find water available at the drinking water faucet next to the main sink faucet. So I happily used it thinking it was filtering the water I used in my coffee and that I filled my water jug with. Here’s a picture of both faucets at the sink.


But a couple weeks ago I had the occasion to empty out under the sink and try to organize it and that’s when I noticed that there wasn’t a filter cartridge in the filter head assembly! I’d missed that during the mad dash to move in. There is a diverter installed in the head so I had water at the faucet though. Huh. It comes with the diverter in order to cap it off if the pink antifreeze is used to winterize the RV.

A quick online check of the device, and I found that the Everpure Water Filter System is still made. It’s sort of the Cadillac of water filters. You could pay upwards of $350 for the the head and filter cartridge, plus labor to install if you want. I found a filter out of their many optional filters I thought would work for me and checked the price online. They were going for $62 and UP! The highest price I saw for just their filter cartridge was $150. Yikes!


Well, now, yes, they do have some nice filters, but so does Culligan and I soon found that the equivalent Culligan filter is only $18, and Amazon carries it. And in my ‘might need someday’ pile of RV parts I happened to have a Culligan filter housing I picked up for free from a recycling table at a RV park several months ago. So decided to do a swap rather than go with the expensive OEM filter.

There’s not much room under the kitchen sink, but there’s a lot more than most RV undersink cabinets so I’m happy about that. Still, it’s not much fun working under there.


First part of the project was to remove the assembly shown below, disconnecting the 1/2″ water supply tubing and the 1/4″ tubing that supplies both the filtered faucet and also branches off to supply the ice maker in the refer.


The RV’s supply line is 1/2″ PEX circa 2002 and I quickly ran into a problem of finding something that would work to mate up that old PEX with the newer plumbing parts made for the new PEX, which is what all the stores around here carry now. Gah! Required several trips to Home Depot, Lowe’s and one trip to Ace Hardware trying to figure out what’s needed. Each time carrying the newer Culligan head with me trying to come up with a method to connect it all up.

The Culligan filter head I had had been modified a bit by the previous owner and had short stubs of 3/8″ tubing inserted into the filter head in/out fittings. Then on the input side there is a male style plastic 3/8″ threaded plumbing fitting. I needed to mate that up to the male 1/2″ plumbing fitting that’s under the sink. The output side of the filter head only required a 3/8″ X 1/4″ brass compression coupler and that was easy to find.

The Lowe’s plumbing guy recommend a method that sounded good and on his recommendation I bought a 1/2″ FIP X 3/8″ FIP brass reducing coupling to mate up the old plumbing to the newer Culligan head. That allowed the use of nearly all the parts I had on hand from the old setup. And didn’t require cutting into that older PEX plumbing under the sink. It would have been problematic to cut the old PEX and join it with various new parts. But, nothing ever goes smoothly and no matter how much I tightened that reducing coupling, or how many layers of teflon tape I used on the threads, (3 is recommended, I used that and up to 6 while testing), there was always a continuous drip, drip, drip. Put it together, test, find it dripped, tear it apart, run to the store trying to find a fix, come back, retest. And on and on.

Here’s a shot (below) of the Culligan filter housing all connected up. The filter cartridge is inside that lower sleeve part which unscrews from the head when it’s time to change the filter. You can just see a drip forming on the brass coupling there. That’s what was giving all the trouble. Sometimes it would leak in the back of the brass coupler as shown here, other times at the front of the coupler, then sometimes both places as I tried differing methods of sealing it. The 1/2″ PEX supply tubing is shown here in the foreground, the 1/4″ plastic tubing in the background up against the wall. The original plumbing is everything in the foreground of the picture up to the brass coupler. Everything after the new brass coupler came with the Culligan housing. Past that, the 1/4″ tubing is original to the RV. Mating up the 1/4 tubing to the filter head using compression fittings was a breeze and once tightened down, never leaked.


Despite what the plumbing guy at Lowe’s had told me about not needing anything other than the brass coupler and teflon tape to join up the 1/2″ to 3/8″ connections, since I hadn’t been able to get the coupling to stop dripping no matter how much teflon tape I used, I had an idea of using a plastic ‘O’ ring, inserted inside the coupler between the two pipe surfaces. I thought when the three parts were tightened down, the flat surfaces of the two plastic plumbing parts would contact the rubber ring and seal due to compression. Seemed like a good idea. First I tried a small ring that fit neatly into the coupler. It was slightly larger in diameter than the hole for water in the smaller pipe fitting. There was still a leak. Unfortunately, trying to get it to stop, I tightened the parts so much it distorted and tore the ‘O’ ring…and leaked even worse, but still much less than when just using the teflon.

Hmm. OK, there’s that old adage, if one is good two must be better…so I took it apart for what seemed like the umpteenth time, put a new and slightly larger ‘O’ ring in, and also put a new smaller diameter ‘O’ ring that just fit inside the bigger ‘O’ ring. Both rings are large enough diameter they don’t block the openings, allowing full water flow. Those two rings gave a nice rubber surface for the 3/8″ & 1/2″ pipe surfaces to mate and seal to inside the brass coupler. This time when I screwed everything back together, I was careful to hold the assembly so the rings wouldn’t shift or end up crooked as I screwed the fittings together. Don’t know which ‘O’ ring actually stopped the drip, but this time they did, and I’m leaving them in there. [FYI: I had bought one of those multi-size ‘O’ ring kits at Harbor Freight for a couple bucks a few years ago. Having them around comes in handy occasionally for RV work.]

TADA! It worked! No more drips. Perfectly dry so far and it’s been 48 odd hours now. Today, took back at least $15 of plumbing parts that I’d bought…’just in case’ or thought I’d need. The Culligan US-600A 3/8″ undersink drinking water filter is not as fancy as the other model I removed, but it’ll do the job, at a lower cost. The filter cartridge I bought for it (it was without one when I picked it up) has the exact same filtering specs, microns and whatnot, as the expensive setup does. And replacement filters are much easier to find as Ace Hardware carries them nationally, and of course, Amazon carries them too. Total cost for this project ended up at $29, including $18 for the filter purchased from Amazon. The filter is likely to last a year. There are cheaper filters available but I decided on the D-30A Level II. As I said earlier, I had found the Culligan head on a recycling table so that was free though if I’d bought it it’s under $40 (follow Culligan…etc., link above).

While I’m driving around the country the next few years I’ll look for a gate valve I’ll be able to get cheap or free (have you noticed how expensive plumbing parts have gotten lately!!) to put inline in that 1/2″ PEX supply tubing feeding the filter. As an emergency and service shut off. The original filter housing had one built in but this Culligan doesn’t. Probably a minor issue since it’s generally used only when you’re winterizing and I seldom do that being a full timer and all.

And here’s how it looks all set up and filtering. Check it out…no drip!


Anyway, that’s that. Here’s some nice filtered water coming out of the water spigot. Cheers!


I’ll still use the external filter for problem RV parks occasionally but most of the time, I won’t need to bother with it now that there’s an under sink filter.

Thanks for visiting.


One Response to Drinking water filter…

  1. Samg says:

    My motorhome sits in storage. But will be rolling soon. Trans leaks when sitting. Have to install new awning material sometime. But I had to laugh when you said the old plumbing doesn’t match. Neither do modern roof vents.

    Don’t know how bad your tranni leak is, but heading up that steep hill in Alaska outside of Juneau a few years ago, I sprung a leak at an external hose coupling so I was leaking tranni fluid like crazy. Stopped several times to add tranni fluid & stop leak. I’d be able to limp along for a couple hundred miles before I’d have to add fluid and more stop leak. One time it worked well enough that it hardly leaked for two days travel. Traveled from Juneau to Prince George to find a decent shop, so around 1,000 miles. So maybe try some stop leak juice? If it’s a minor leak that only shows up when it’s sitting, might be a semi-permanent fix.

    At the beginning of the summer my girlfriend decided she was going to remodel her bathroom. Fun. Her brother installed most everything, but I assisted. Diverter for the tub leak. Russ resoldered the fittings. Disassemble, reassemble. Then I was in the crawl space soldering the supply lines. Yuk. Had never had much luck with that. Used my largest torch tip and plenty of NEW solder. Hooray! Fine job!

    Soldering is in my skill set. Learned very young. Copper plumbing is easy for me…usually. But I haven’t worked with it for years. Trick is proper prep.

    Last year I replaced the toilet in the motorhome because the water would leak down past the flapper losing an air seal. By the way it still does, slowly. When removing the old toilet, PO hadn’t cut away the rug underneath and I was glad I was replacing it because the base was cracked around the bolt holes. When it was time to hook up the supply, Old and new PEX didn’t match. And plumbing is a mystery to me. So off to Lowe’s with the toilet and a piece of old tubing. The assistant fixed me up!

    Whoa. That’s great that you found a plumbing guy that knows what he’s talking about. Usually they don’t in those big stores.

    Working on these beasts is as much fun as working on a new vehicle, a chore. So I sympathize with you. Twice as long and twice as hard to work on in my case. But thanks for your blog it helps me keep in touch.

    I’m happy you enjoy it! And thanks for the kind words. I have to say, looking back on this project, I’ve worked on worse. I hope any other mods I have to do are as easy.

    In closing, today is my birthday (Labor Day) and we went for free breakfast this morning. Free buffet this after- I hope you’re having an enjoyable holiday.

    Happy B’day and many more. The sky is turning blue here in Portland in honor of your b’day perhaps, so maybe it’ll turn into a nice day afterall!

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