Wanta Drink ?
Howdy
Water. . It’s one of the most important parts of the self-contained RV lifestyle and something a buddy of mine has a problem with. His “fresh” water tank was pouring out green stuff and stank like – well, it was bad !!
For the most part, there are few problems and so we tend to ignore the workings of the RV water system until something goes wrong.
There are two basic types of fresh water supply systems for RV’s. The older method is the pressure system where an air pump is used to pressurize a metal tank containing water while on the road and the city water connection provides the pressure to the tank when parked with hook-ups. Because of inherent problems with this system it’s not used any longer by manufacturers, although you will still see it on older RV’s.
The system used for the last several years is the demand system. With this system the water is drawn from a non-pressurized fresh water holding tank by a 12 volt DC water pump which supplies water to the RV and also allows the use of pressurized city water in the RV by going around the pump. Let’s examine the demand system in more detail, after all, you can’t always call a plumber when you’re on the road.
The Tank
The water tank is usually constructed of natural white low density polyethylene material which is durable and easy for manufacturers to mold into the shape best suited to fit a particular RV. These tanks normally have three hoses in them. The freshwater fill hose is connected from the outside filler connection to the tank via a 1 1/2 inch corrugated hose. The second opening in the tank is a vent line which is a 1/2 inch hose that runs from the tank to the fresh water fill port. The last opening is the 1/2 inch line from the tank to the water pump. There will also be water level sensors for the tank which are connected to the monitor panel inside the RV. These may be the radar type which are applied to the outside of the tank or the probe type that are screwed into the side of the tank. If you have been RV’ing for any length of time, then you know that the probe type monitors sometimes are a bit erratic – that is, they lie ! You can often fix the problem by draining the freshwater tank and removing the probes. Clean them with fine steel wool or a 3-M Scotchbrite pad to remove mineral deposits, wash the probes and then re-install them into the tank.
Sometimes the worst happens and the tank develops a crack or split. Here you have three options. The first is the use of a plastic epoxy repair kit made for fresh water tanks like the Syon repair kit. Solvent cement or fiberglass resin will not bond to polyethylene tanks, the Syon kit will. The second option is to find a shop that can do plastic welding. This is done with a special hot air gun used to soften and melt the area of the area around the crack and then fill the crack by “welding” with freshwater safe plastic rods. This type of repair is more of an art form and it’s difficult to find someone that can do it well. The third option is to replace the water tank with a new one. Fresh water tanks are priced by their complexity and size. A 3-5 gallon tank will cost around $60.00, a 41-45 gallon tank about $175.00 and a 100 gallon tank a bit over $300.00.
The pump
The water pump is called a demand type because it has a pressure sensing switch built into the nose of the pumping chamber. This switch turns the pump on when the pressure drops because of a faucet or other device drawing water from the system. The pump shuts off when the demand is finished and is normally set to hold 45 pounds of pressure in the water lines. If there are leaks in the system the pump will attempt to meet this “demand” and will run until the line pressure is restored. This is called burping and is a sign of a leak somewhere in the water system. The pressure switches are factory set but can be adjusted if needed. There is normally a 50-mesh screen or filter used between the tank and the pump to prevent any trash getting into the pumping chambers. A backflow preventer valve is used on the pressure side of the pump to prevent the city water connection from filling the water tank. This valve is usually built into the pump. The newest pumps are constant damand flow where the pump will speed up or slow down as the damand for water changes, like if you are in the shower and “someone” else turns on a water faucet. These are computer controlled units and they do draw up to 15-amps of power so you may need to install a larger wire to power them.
City Water Connection
When you are parked in a campsite with water hookups a connection is made between the campground hose spigot and the RV. This is called the “city water” connection. There is a backflow preventer installed in RV’s city water connection to prevent the water pump from moving water from the freshwater tank out of the RV through the city water hose connection. To connect the RV to the campsite freshwater connection always use water hoses designed to provide freshwater for drinking use. These hoses are normally white with a blue stripe. Because these hoses are made for RV use they are not reinforced against high pressure like a garden hose, so they must be protected from excessive pressure. Plumbing in RV’s is designed to operate at around 45 pounds water pressure. City water pressure can be well over this amount and can damage RV water lines. To prevent over-pressure damage you need to use a 45 pound water pressure regulator between the water faucet and the freshwater hose going to the RV, this will not only protect the lines in the RV but will also prevent the water hose from being blown-up !
Water lines
The last twenty years have brought several advances in water line technology over the old copper and hard PVC plastic pipe water lines for RV’s. The first major advance was Polybutylene (PB). This is a gray colored somewhat flexible pipe used for both hot and cold water applications. The fittings designed to be used with this pipe are either Qest flared cone-and-nut fittings or copper barbed fittings with copper crimping rings. The newest water pipe is Polyethylene (PEX) which is clear or a transparent red color. This pipe uses Flair-It connections which can also be used on the older PB pipe. Flair-It connections can be used to repair small splits and kinks up to 2 inches in length in either PB or PEX by cutting out the bad section and inserting a Flair-It union into the gap, not a bad thing to keep in the toolbox. You can get the parts from a RV shop or some home supply stores.
Hot Water Heater
The hot water heater in an RV is a sturdy and almost care-free machine. You may notice that sometimes the pressure relief valve seems to be leaking. The first reaction is to replace the valve – wrong answer. The relief valve is designed to vent excess pressure from the water heater and in most cases if it seems to be leaking, it’s just doing it’s job. The most likely culprit is that the air bubble that is supposed to be in the top of the hot water tank has been lost as the air was dissolved into the water. To correct this problem turn off the heat source and water supply for the water heater and open the pressure relief valve. Next remove the plug or anode rod from the bottom center of the water heater to allow all the water to drain out. Also open all the hot water faucets in the RV to ensure that all the lines are drained out. Now replace the drain plug/anode rod and close the relief valve. Turn on the water pump to start filling the tank. When water begins to come out of the hot water faucets close them. There is now a large air bubble in the top of the tank and the job is done.
Sanitation
Is clear water clean ? Not always. Is smelly or stale water bad for you ? Not always, it just tastes that way. The fresh water tank and lines need to be sanitized anytime water tastes odd or on an annual basis. Empty the water tank and lines using the RV’s built-in drain valves. The rule of thumb is 1/4 cup of chlorine bleach for every 15 gallons of water tank capacity. Pre-mix this in a gallon of water and pour it into the freshwater tank through the water filler. This makes a very strong, (200 parts per million), disinfectant solution as suggested by the EPA. With a half tank of water, drive the RV for 5 to 10 miles to slosh the mix around in the water tank. Fill the tank with fresh water and let the RV sit for several hours. Now, one at a time, open the water faucets in the RV until you smell chlorine in the water. Close the valve and let the mixture sit for several hours. Open all the faucets and let the water pump empty the tank and lines of the chlorine mix. Now drain the water tand then fill the water tank with water and flush the system by running the pump until you no longer notice the chlorine smell.
To remove any lingering chlorine taste mix a half cup of baking soda in a gallon of water and add it to a full tank of water. Drive the RV for a couple of miles to mix and slosh around in the tank and then empty the tank by opening all the faucets and tank drain the running the water pump until the tank is empty.
Accessories
Water filters placed in the hose going to the city water connection will prevent sand, minerals, lead and other sediment from entering the RV’s water supply. You can also add an activated carbon type filter that will remove most bad tastes such as iron and sulfur from the water supply. You can also use the water filters on the hose to fill the fresh water tank.
Accumulator tanks have an internal rubber bladder that divides the water chamber from a sealed air pocket. The air chamber is compressed by the water and as water is used it slowly expands, maintaining pressure on the water system. This reduces the number of times the water pump must cycle to provide pressure to the faucets. The tank can be mounted anywhere in the cold water side of the system past the pump. Don’t use one of these with the new type constant damand pumps – it runs them crazy because they can’t “read” the true damand for water.
The water system is something that we generally don’t think about until it’s no longer there, and with a bit of understanding and maintenance it will be there to service us whenever we need it. As for my buddy, well, it took three days and four – thats 4 gallons of bleach !
Latter – –
The Old Ranger