Many Reverse Osmosis Deionizer units designed for aquariums attach to a sink. They are all plumbed with small 1/4" lines and the input has a 3/4" hose/faucet adapter. The 2 outputs are 1/4" waste water and deionized water. Throw 1 in the drain and one in your bucket and turn the tap on. Figure on about 1 hour to get 5gallons of water.
Municiple water pressure isn't high enough to puncture the membrane and get a high flow of RO water. In industry they use pumps to increase pressure to 300+PSI and get high efficiency. At home you have around 35-60PSI so expect approx. 1hour per 5 gallons of water.
You can plumb your filter directly to your water lines and drains of the house if you want since the units use standard 1/4" poly lines. You may also get a kit with a tank for drinking water. The water after the RO membrane goes to the tank for drinking, and some of the water after the RO membrane goes to the Deionizer for the aquarium. You get 2 outputs. The tank water can be redirected to single faucet for drinking water.
My setup has a whole house sediment/chlorine charcoal filter. This goes into a water softener. The output of the water softener goes to a shut off valve and into a male 3/4" hose adapter. My RO/DI unit is attached to this with it's faucet adapter. I have the output 1/4" tube hanging in a 5 gallon bucket for my water changes. I put a 25' 1/4" drain tube on the waste water...bought it at home depot for $3. When I want water I run the drain tube to the sink and hit the shutoff valve to start filling the bucket. Takes about 1 hour.
My unit is made by Aqua FX - Home
I have the barracuda 100 gallon/day unit. I bought it from an online aquarium store but you can buy direct form the company as well. Great unit. Units made for aquariums seem to be 1/4" poly tubing with a deionizer filter and a faucet hookup.