Complexity

Beginner

Cost

$251-500

Introduction

Install a reverse osmosis system under your kitchen sink to supply purified water. You can do it yourself in less than 2 hours.

Reverse osmosis water filter benefits, costs and performance

If you buy lots of bottled or filtered water or are worried about 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 reverse osmosis system costs $150 to $300, plus $100 to $200 annually for replacement filters.

Reverse-osmosis filters remove many pollutants and chemicals from water, separating them from the water and flushing them into the drain line. The purified water is then fed to the storage tank or the sink’s spout. However, reverse-osmosis filters remove the minerals that give water its taste, so try a gallon (available at most supermarkets) before buying a system.

Tools Required

  • 4-in-1 screwdriver
  • Adjustable wrench
  • Utility knife

Materials Required

  • low-pressure tire gauge
  • reverse osmosis filter system

Project step-by-step (5)

Step 1

Mount water supply feed

Push the plastic supply tube onto the inlet valve, then tighten the nut a half turn past hand tight.

Mount water supply feedTMB STUDIOTMB STUDIO

Step 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.

Attach the sink faucetTMB STUDIOTMB STUDIO

Step 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.

Connect the drain line adapterTMB STUDIOTMB STUDIO

Step 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.

Mount the storage tank and sanitizeTMB STUDIOTMB STUDIO

Step 5

How to recharge a reverse osmosis holding tank

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. 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 it’s 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.