Your holding tank can be as simple as a rubbermaid trashcan or some other kind of tub. Many of the RO
kits that come with pressurized holding taks are intended for 'drinking water' installs. This is where a faucet is mounted at your sink and the pressurized tank delivers RO
water under some small amount of pressure to the tap. Else the user might have to wait 3-4 minutes to fill a glass of water vs a few seconds with a pressure tank.
The absolute simplest method of getting water to the RO
unit is to use what they call a sattle valve. This valve clips onto your cold water PVC
plumbing. THere is a small needle that puts a little hole in the PVC
valve to supply the RO
unit. There is a seal around this needle to prevent leaks. Another method is to use a 3/4 hose to 1/4 tubing adaptor. This would screw onto a faucet (like on the outside of your home or in your basement by the washer hookup) and then you would use a compression fitting to attach the 1/4" tubing that runs into the RO
To get water out of the holding tank you simply scoop it out like I do or if you want to be fancy you can elevate the holding tub with blocks and then afix a faucet to the tub and use that to drain water into a bucket.
unit will come with some drain line. Dependingon your setup you might need longer. If this is teh case its just 1/4" tubing that you can get at any home improvment store.
drain can be elevated to some degree. You can even shoot the drain out a cracked open window onto the yard in the back. I have mine doing into a sump pump that then pumps the water up to the house drain that is so convently located half way up the basment wall.
You should have a 1:4 ratio of good to waste water.
You would need a shutoff valve to have it turn off so to speak when the holding tank is full.
I would recommend looking at http://www.aquariumwaterfilters.com
They are not only a sponsor but have a load of useful information on RO
filters in general.