Benefits, costs and performance
If you buy lots of bottled or filtered
water or you're worried about your
tap water, a reverse-osmosis water filter
can be a good investment. They can provide
10 or more gallons of drinking water
a day. A system costs from $150 to $300, plus $100 to $200
annually for replacement filters.
Reverse-osmosis filters remove many
pollutants and chemicals, separating them
from the water and then flushing them
into the drain line. The purified water is
then fed to the storage tank or the spout
on the sink. However, reverse-osmosis filters
remove the minerals that give water
its taste, so try a gallon (available at most
supermarkets) before buying a system.
Install a reverse osmosis system
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Photo 1: Mount water supply feed
Push the plastic supply tube onto the inlet valve, then tighten the nut a half turn
past hand tight.
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Photo 2: Attach the sink faucet
Feed the water supply line and the
two waste lines up through the hole
in the sink and through the gasket and
faucet base, then attach them.
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Photo 3: Connect the drain line adapter
Install the drain line adapter just
below the sink and above the discharge
from the disposer and/or dishwasher.
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Photo 4: Mount the storage tank and sanitize
Before using the system, sanitize it and then fill and drain it to rinse it clean.
Check all the fittings for leaks.
First, hang the filter assembly on the
back or side wall of the sink base (or in the
basement close to the sink location) at the
height specified in the instructions. Turn
off both the cold and the hot water shutoffs,
and then install (after the cold water
shutoff) the tee or saddle valve included
with the unit.
Cut the color-coded water supply line
so that it's above the cabinet base and
won't get kinked. Fasten the plastic tubing
to the supply valve (Photo 1).
Shorten the supply and waste lines to
the faucet to eliminate excess tubing, but
don't cut the larger black waste line yet.
Attach the lines to the fittings on the base
of the faucet (Photo 2). The black waste
lines feed through the base of the faucet to
keep them above possible sink backups,
but they have no connection to the supply.
Fasten the faucet to the sink, then install
the drain line adapter under the sink basket.
Cut the waste line so that it flows
downhill with no loops, then push it into
the adapter (Photo 3).
Set the storage tank into place and
install the final water line. Sterilize and fill
the system according to the manufacturer's
instructions (Photo 4).
Recharge a reverse osmosis holding tank
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Check the tank's empty pressure
Unscrew the protective cap and check the tank pressure. Inflate or deflate with a tire pump to achieve the manufacturer's recommended pressure (usually 5 to 7 psi).
If your reverse osmosis filtration system doesn't deliver as much water as it did when it was new and you've changed the filters and membrane, the problem may be an undercharged or leaking holding tank. The tank uses a traditional tire valve-style stem that can lose air over time. When the air pressure drops, the bladder can't push out as much water.
Here's how to check the pressure. First, you'll need a low-pressure tire gauge (one choice is the Victor Tire Gauge Low Pressure 1 to 20 psi; $6 at amazon.com). You can't use an ordinary tire gauge. Next, turn off the water supply valve to the filter system and shut off the valve at the top of the holding tank. Disconnect the tubing at the tank valve. Dump all the water out of the tank. Then check the air pressure as shown above. Adjust to the recommended pressure. Then reinstall the tank and tubing and turn on the water.
Once the tank is filled, note the filled pressure. Wait a few days and check the pressure again. If the pressure is the same, you're done. If the tank has lost pressure, try replacing the valve core (available at auto parts stores). If the new core doesn't solve the problem, replace the tank.