How to Install a Reverse Osmosis Water Filter | Ask This Old House

In this video, This Old House plumbing and heating expert Richard Trethewey removes the impurities, VOCs, and excess minerals from water with a simple reverse osmosis water filter system.

Plumbing and heating expert Richard Trethewey heads on a house call to help a homeowner with a water issue. After the homeowner explains that she’s had a problem keeping aquarium fish alive, Richard surveys the plumbing system and comes up with a solution: a reverse osmosis water filter.

Difficulty: ⅖
Cost: Around $200
Time: 4 hours

Where to find it?

Richard removes an old sprayer hose from the sink to install a dedicated system faucet. He uses the ⅜" and ¼" red tubing to connect to the cartridges and the water tank. Richard positions the connector above the trap and drills a 7/32" hole into the drainpipe. He checks that all tubes are fully pushed in before turning the cold water supply back on.

Tools:

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From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment—your home.

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How to Install a Reverse Osmosis Water Filter | Ask This Old House

[taoyen]

How to Install a Reverse Osmosis Water Filter: Done in 1 minute, the other 7 minutes was just explaining the house and water tests. Got it!

[cowcabobizle]

Always awesome to see Richard explain plumbing!

[RatKindler]

Would have liked to see the resulting water tested too. Also, couldn't they have just adjusted the pH of the water before adding the fish instead of going the reverse osmosis route? Aren't you supposed to do that for tropical fish anyway?

[stevehowe]

One thing I would have done differently is install the RO system in the mechanical room and then run lines to the basement sink and the kitchen sink as well as any refrigerator icemaker‘s you have. This way you get the RO water at multiple locations throughout the house and just not one. I’ve had an RO system for over 30 years. One of the best investment a homeowner can make.

[kellyrjohnson]

For all we know they never properly cycled the tank and there's zero bacteria available to reduce ammonia. I'd like to think they tested for that before going assuming it's a pH issue. Not that it can't be, but fishkeeping often involves a lot of patience and prep before just buying fish, tossing them into a tank and wondering why they're dead in a day.

[wilsonxyz]

She also need to aerate the water first before she put the water into the aquarium. It's not the chlorine since it's well water, but because the dissolved oxygen level from the well water is very low.

[CARLOSTREUIL]

We had a 10 gallon aquarium for years with a bottom under gravel filter. We changed the water every few months. We purchased 2.5 gallon carboys of drinking water and just dumped it into the tank. The fish loved it and lived forever. Much cheaper and less complicated. The drinking water had been run through an RO unit.

[Silky_boi]

Ok this is crazy I just saw the older video of Richard installing an RO system!?

[geeoye]

TOH team, thanks for detailed explanation of the RO system. Can you do another review on one of the newer tankless RO systems. Per their marketing, that saves lots of water and more efficient than the legacy 5 or 7-stage system. Thanks as always.

[chibbyylol]

Guys the faucet is there so they can drink it as well lol; don’t think it’s ONLY for the fishies

[mariebee]

Where did you get that faucet? I love that it's a duel faucet.

[SlackerU]

Interesting but we didn't test-strip the RO water.

[skull]

did she use soap to clean the fish tank? soap sinks into the rubber between the glass connections

[johndoe]

Confused by his comment at the end. The filters will fill the tank in 1-3 hours, but he said the water won't be clean for 24 hours. What is happening with the water sitting in the tank between 1-3 hours and 24 hours?

[MandoFettOG]

Wouldn't it be easier to just buy a few Gallons from the store?? How often do you change the tank water??

[JohnAranita]

You must buy API Quick Start or Tetra Safe Start. Both have bacteria that when you introduce the bacteria in the aquarium water, the biological filter is immediately started. The bacteria consumes ammonia and nitrate, which are harmful to fish.

[MickS]

Fish should not be kept in pure RO water, they need minerals to properly osmoregulate. When keeping tropical fish its much better to find fish that will thrive in YOUR water. Fish will adapt to stable, consist water parameters. In the case of this homeowner, high ph and high hardness would be perfect for African Cichlids or Livebearing fish.

[geomodelrailroader]

good to see this I will need to install one of these

[diyenthusiast]

TOH: Can you please also provide a link to the water test kit that was used in the video ?

[dipeshnayyar]

That plumming is out of this world should belong in the muisuim