Connecting a refrigerator to an under sink reverse osmosis system is mostly a tubing exercise, and the two things that decide whether it works well are where you take the connection from and how the run is made. Both are easy to get right and both are commonly got wrong, producing a dispenser that trickles and a household that blames the membrane.
Where to tee off
Take the connection from the treated water line after the storage tank and after the polishing filter, so the fridge gets the same water as the kitchen tap. A tee fitting at the faucet's supply line is the usual point. Fit a small shut off valve immediately after the tee, which lets the fridge be isolated for appliance work without shutting down the whole system. Do not tee off before the tank, which would feed the appliance directly from the membrane at production rate.
The tubing run
Use the tubing size the system specifies rather than mixing diameters, since a mismatch at a push fitting is the classic leak that appears the following day. Keep the run as short and direct as the kitchen allows, and avoid tight bends, long horizontal loops behind cabinets and any point where a cabinet drawer can crush it. Leave enough slack at the appliance end that the fridge can be pulled out for cleaning without straining a fitting, and secure the tubing along its length.
Pressure and capacity at the far end
Pressure at the dispenser is what the storage tank can deliver minus what the run takes away, so a long or convoluted route shows up as a slow dispenser. If the fridge has an ice maker, expect it to draw in bursts, which can empty a small tank and leave the kitchen RO tap trickling while it refills. A larger tank, a permeate pump or a higher production membrane all address that, and it is far easier to decide before the tubing is run.
Commissioning it
Open slowly, then check every joint by hand and again an hour later, since push fittings often weep only after pressure settles. Discard the first several batches of ice and the first litres from the dispenser, because the line and the ice mould hold old water and any carbon fines from a recent filter change. Then keep the system's prefilter schedule, since everything the fridge dispenses now depends on it. Our whole house RO guide covers larger scale distribution.
Questions people ask about reverse osmosis system for fridge
Where should I tee off for the fridge?
From the treated line after the storage tank and polishing filter, with a shut off valve immediately after the tee.
What tubing should I use?
The size the system specifies. Mixing diameters at push fittings is the classic leak that appears a day later.
Why is the dispenser slow?
Pressure lost along a long or convoluted run, or a small tank being emptied by the ice maker's burst draw.
What should I do after connecting?
Check joints by hand and again an hour later, then discard the first several batches of ice and the first litres of water.