If you blow through a straw, you know that – the bigger the straw – the easier it is. The same holds true for the waterlines in your home. If your piping is undersized, whether that be due to corrosion buildup from minerals in your water or improper sizing in the original installation, the volume and pressure of water flowing through your system will be less than needed for day to day operations. For every foot of piping and every fitting that your supply must pass through, there will be an associated pressure loss. Each fixture in your home requires a minimum pressure and volume to operate properly, and if not satisfied, will not fulfill its role in it’s designed manner.
In existing homes and buildings, it can be very expensive to remedy undersized piping, so if given the opportunity…do it right…from the start. As a minimum, your water service (that run of piping from the street to your main shutoff valve) should be 3/4 inch. If your home has 3 or more water closets (toilets), 1 inch would be appropriate. Of course – if your water service is extremely long and/or the vertical distance between service and house is great – you may want to up-size from these recommendations, as friction losses become an issue. (The friction created by the water in contact with the walls of the piping = pressure loss, and for every foot of vertical elevation, approximately 0.5 p.s.i. will be sacrificed.)
Inside your home, full size piping (same size as water service) should extend to your hot water tank, and both hot and cold branch lines to fixtures should be served from a full size main. As a general rule – a bathroom will be served by full size line, but each fixture within can be served with smaller line (usually 1/2 inch). Outside faucets should be protected from freezing during cold periods by being “frost-free” or having a shutoff valve located within the house. Frost-free valves are constructed of a tube containing the stem, washer and seat, which extends through the oustside wall to an interior warm space, so that when the exterior valve is closed, the tube drains (make sure the valve has grade!), and the water supply is now shut off where it is not susceptible to freezing. If you do not have a valve of this construction, there must be an interior shutoff. During cold periods, the interior valve is closed, and the exterior valve is opened. If there is a drain on the side of the interior valve, it should be opened to allow any water in the downstream piping to be evacuated. During warm periods, the sequence is reversed – close outside faucet, close drain valve and open interior shutoff valve.
If your municipal water service pressure is high (over 75 p.s.i), a pressure reducing valve (P.R.V.) should be installed just downstream of your main house shutoff. The P.R.V. helps to reduce water usage, protects your home from water hammer, and by extension, helps protect the piping and fixtures from early failure . If you have a pressure gauge that will adapt to an outside faucet, check the pressure while no other water is being used, and adjust your P.R.V. to an appropriate level (50-60p.s.i). This is accomplished by loosening the stop nut below the adjusting bolt, and with a screwdriver, turning the bolt clockwise (in) to increase and counterclockwise to decrease the house pressure. Right pressure, right size, hammer arrestors where applicable, and you have a happy water system!
Common materials for water lines and services are copper, polyethylene(pex),CPVC, and joining methods differ for each. Copper piping and fittings may be soldered or connected with a variety of push-on fittings (sharkbite for example). Pex(cross-linked polyethylene) can be connected using push on fittings as well, or if you have the correct tool, crimped with fittings and malleable rings. CPVC is a glued system generally, but again may make use of push on fittings. Do not mistake PVC for CPVC, as the former material is not approved for hot water distribution, and will become brittle and crack.