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Mod #70: Drinking Water Filter

Posted By ModMyRV On February 14, 2009 @ 3:31 pm In plumbing | 12 Comments

The drinking water filter mod is one of those things that should come straight from the factory for all RVs. The way RV holding tanks and plumbing systems are designed and utilized tends to promote bacterial growth if not sanitized on a regular basis. And more importantly, it’s not all that uncommon to get a bad batch of water from a seemingly safe water source. In addition to sanitizing your RVs plumbing system frequently, filtering the water before it get’s in to your system goes a long way in preventing bad water taste and potentially harmful parasites and bacteria from having their way with your system. The last thing you need when camping is to be enjoying your toilet more than the outdoors.

Mod Difficulty:

Although there are several approaches to providing clean water for your RVing needs, this mod focuses on drinking and cooking water filtration. Of course, filtering your entire RV water supply system is an option but it is not always necessary. Most water sources are chlorinated and have enough protection to minimize bacterial growth. It just might not taste very good. Again, sanitizing often and not letting your water pipes, water heater, and fresh water tank sit without use will stave off 99% of bacterial growth. Assuming you have decent water to start with, the drinking water filter will provide great taste and protection in a simple to use manner.

The simplest approach to modding your RV with a drinking water filter is the countertop style filter. This system uses a standard, replaceable 10-inch filter cartridge and houses it in a plastic canister that sits on your counter. The water is fed to the unit through a tube hooked up to your sink faucet, and includes a spigot to serve the filtered water. This has the advantage of being portable. You can take the filter system with you for use in another RV, or even your home for that matter. If you are looking for a quick and easy way to get great tasting water, then your mod work here is done.

The most arguably popular drinking water filter mod though is the permanent-mount under-sink type, where the filter cartridge is mounted under the sink and the dispenser is mounted to the countertop or sink. The water supply to the dispenser is connected via a tee fitting placed in the cold water supply pipe used by the sink faucet. This makes using the dispenser easier and requires less counter space. And the filter housing is placed in an out of the way location under the sink, in a cabinet, or other convenient spot.

Doing this mod is pretty straightforward, but requires a few tools you might not have handy in your mod tool set. These are a PEX or plastic tubing cutter, and a hole saw. Using a tubing cutter will help ensure there are no burrs on the tubing after cutting, which reduces the chance of a leak at the fittings where the tubing slides in. The hole saw is necessary since the dispenser is secured by a threaded shaft on the bottom of the dispenser, which must go through the sink or countertop, and is secured underneath the sink or countertop using a large washer and nut. Some dispensers only require a 1/2″ hole for the threaded shaft so you might not need a hole saw. A 1/2″ drill bit will work. Others may need a larger mounting hole so a hole saw is a must.

Once you have the right tools for the job, installation is easy. Start by locating where you want to mount the dispenser. If you plan to mount the dispenser through the countertop, place some masking tape over the area you will be drilling through to help prevent splintering. If you plan to mount the dispenser through a metal sink shoulder, drill slowly if using a hole saw to prevent overheating the bit. After drilling the dispenser mounting hole, place the dispenser mounting shaft through the hole and secure with the supplied hardware.

The next step is to locate a suitable place for the tee fitting in the cold water line going to the sink faucet. The tee fitting taps in to the line and provides the water supply connection for the dispenser. You can tap in to any cold water line but under the sink is the most convenient. Here is where you use your handy dandy PEX tubing cutter. Before cutting, be sure your water pump it switched off and all pressure in the line is relieved. Otherwise you’re in for a real mess. Now carefully cut a 1″ section out of the cold water line, which will require two cuts. If you have enough room to move the lines away from each other 1″, then you may not have to do the second cut.

Water filter kits usually come with all the fittings necessary for a typical installation. This mod uses a plastic tee fitting which slips in between the cut tubing and a brass shutoff valve that serves both to provide the water supply to the dispenser and to turn off the supply if you need to change the filter or winterize. Thread the brass fitting in to the tee fitting using plumbers tape around the threads to prevent leakage.

Next, the water supply tubing needs to be attached to the brass shutoff valve. Don’t worry about the length of the tubing at this point. The idea here is to secure the tubing to the fitting first since doing this requires a couple of end wrenches to secure. You might not have much room to use the wrenches in a tight compartment. The brass fitting is a compression type fitting so you need to slide the compression nut on first, then the small compression ferrel. Insert the tubing in to the fitting and tighten the compression nut fairly tight but not too tight.

Now secure the plastic tee fitting to the cold water line by sliding the round plastic threaded nuts on to each side of the cut tubing, then insert the tee fitting. Secure the nuts to the fitting taking care to not over tighten. You can use pliers to do this but make sure you hold the fitting body securely so you don’t damage the water line.

The next step is to mount the water filter. Find a suitable location near the the tee fitting you just installed. The mod shown in the pictures uses a simple plastic bracket that the filter snaps in to. Secure the bracket and snap the filter in to place. Now you can measure how much tubing you need to go from the dispenser to the filter, and from the filter to the shutoff valve. Measure the distance for each and then add 6″. This extra tubing will help with any bends required when routing the tubing. Cut the tubing with the tubing cutter to the appropriate length.

Attaching the tubing is incredibly simple with the type of filter and dispenser used in this mod. All you have to do is insert the tubing in to the ends of the filter and in to the bottom of the dispenser. No compression fittings or special tools are required. The tubing may appear to be loose in the filter and dispenser but try pulling the tubing out. You can’t. The fittings hold the tubing in place and water pressure actually prevents the connections from leaking. Just be sure to connect the lines correctly, observing the filter input and output arrows.

All that is left is to do now is turn on the water pump and check for leaks. Tighten fittings if necessary but don’t overtighten. Let the dispenser run for a minute or two to eliminate charcoal sediment in the new filter. Now enjoy a great tasting glass of water!

TipWhatever brand filter you choose to buy, be sure it has been certified by the National Sanitation Foundation, or NSF. The NSF tests water filters to make sure that the manufacturer labels are telling the truth about performance. Avoid “generic” filters that have little or no information on the filter housing or packaging. Also avoid buying solely on price. Cheaper doesn’t always mean good. Remember the Yugo?
TipAlthough the drinking water filter in this mod is suitable for drinking and cooking needs, it does nothing for the rest of the water in the system. If you are not one to sanitize your plumbing system often, you should probably use a whole house filter to minimize bacterial growth and ensure safe water for other uses. See the resources below for filters designed for applications like this.

ModMyRV recommends these parts for this mod:
Culligan RV-EZ-4 RV Drinking Water Filtration System

Hole Saws and Tubing Cutters
16 Piece Hole Saw Kit with Storage Case

General Reference

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