I used one while living in Shanghai. I'd slip tubing over the little tap and run it into my kettle on the floor. Only once did I completely forget about it and overflow a quart or so of water.
You might find this useful. It was a review on Amazon for one of the under-sink units, but seemed quite applicable to any of them on how to get the most out of a system. I copy and saved it in the event I install one at home due to my hard water.
"RO system
Works great, easy to mod
By DCD - December 29, 2012
I have had this filter for 6 years and love it. As one reviewer stated "I love water now". I have found a few ways to take this from a really good filter system to an awesome filter system...
First, don't use a water softener if you can help it. If not, then at least put this before the softener. Water softeners work by removing calcium ions (scale) from your water and replacing them with sodium ions. They usually add Total Dissolved Solids (TDS) to your water and this makes your filter have to work harder, requiring more frequent filter replacements.
Second and probably the most important tip, buy a TDS meter. Don't go by the blinking 6 month indicator light. Chances are your filters will last much longer than 6 months. A TDS meter will tell you for sure. Check your water quality once a month. When your TDS starts to rise, it's time to replace your carbon pre-filter. If it goes back down (will be high at first with a new filter), then great. If not, then replace your carbon post-filter. This will greatly cut down on the cost of replacement filters because you only replace them when needed. More than likely you will not have to replace the reverse osmosis membrane but once every few years. Again, go by the TDS meter to tell you when the filters need replacement. I replace my carbon filters about once every 6-8 months and my reverse osmosis membrane every 2-3 years. Throw the battery away and don't even use the 6 month light...
To get your filters to last even longer, install a whole house carbon filter right after your water pressure regulator, before your reverse osmosis system. You will not only save money by replacing just the whole house element every 3 months or so, you will also save your plumbing fixtures by keeping sediment out of the lines. By pre-filtering the water, most of the sediment will be removed before it ever gets to your reverse osmosis (RO) system which will make those more expensive filters last longer. Also, by using a carbon whole house filter and not just a regular sediment filter, you will remove most of the chlorine from your water. This will remove chlorine from your shower water and from the water you use to water your plants. They will thank you!
Some people have complained about a gurgling noise. This is caused by sludge build up in the drain line. If you take the black line apart, you will see black sludge clogging the line. This causes turbulence, i.e. noise. For maintenance, put a dropper full of bleach in the air break located on the side of the faucet. You can clean the sludge away from the line and inside the key hole shaped air break with a q-tip.
If your want more water output, buy a second air diaphragm tank. I have a 44 gallon tank that I hooked up by cutting the yellow hose that goes to the existing tank, putting in a tee fitting and running a second hose to my 44 gallon tank. You can have virtually unlimited filtered water for cooking, ice makers, home brewing beer, hooking up to an aquarium auto-top off system, etc. This filter system is rated to produce about 14 gallons of water a day, if you need more you can always buy another one and hook them up in series. Just add more diaphragm storage tanks as needed. If you add more tanks to the system, be sure you sanitize them. Place a couple of drops of bleach in the tank before you hook it up. Allow it to fill completely with water (overnight or however long it takes). Then, empty it completely through the faucet before using it. Maintenance on the tank(s) requires that you periodically check the air pressure. Pressure should be between 5-7 psi with 6 psi being the target. This system only pressurizes to about 30 psi and so you will have to bleed off some air from any new tanks you install. Most are pressurized from the factory to 30 psi and you will have to bleed it down to 6 psi to get full capacity from them.
Now if you want pristine water that will be cleaner than any bottled water you can buy, add a de-ionizing filter. On the side of the RO system, there is a blue outlet line. This is your reverse osmosis filtered water that goes up to the faucet... Cut this line and hook it into a de-ionizing (DI) cartridge. I have a dual chambered system on mine. One end of the cut blue line will go into the DI filter and the other end of the blue line goes into the other end of the DI filter. Now all the RO water will flow into a DI filter resin which will strip out all total dissolved solids leaving you with ultra purified, pristine water. This is a must if you want to use this water for an aquarium. This has practically eliminated my water changes, but that's a different discussion... To make DI filter change out easy, be sure to install a cutoff valve before the DI filter so that you can shut off water from the RO system. You can also shut off water without a shutoff valve if you simply unscrew the post carbon filter on your RO system. You will spill a few drops but it's not that big of a deal
On my system, I bought a permanently installed TDS meter. It has two probes, one for water going in, and water going out. I hooked the probes up to the water flow before and after the DI filter by using a Tee fitting with the probe inserted in the water stream. The "in" probe reads water quality before the DI filter, but after the RO system. I use this to monitor the performance of the RO system. I usually maintain 1-3ppm of total dissolved solids coming out of my RO system. If this number climbs, then I know it's time to replace a carbon filter or two... I use the "out" probe to monitor the DI filter. It has a replaceable resin and when I notice any rise in TDS coming out of the DI filter, I will replace the resin. It's just a grain like sand that you dump in the cartridge. Simple to replace. On my system I always get 0ppm of TDS which is about as clean as you can get. MUCH cleaner than any bottled water you will find. It rivals distilled in terms of quality. My DI resin lasts me about 3-4 years. This is with about 4-5 gallons of use per day.
If you do all of these things, you will have a very high quality system that is both easy to maintain and low cost. It's nice having RO/DI filtered water on tap for my fish tank and it makes drinking water taste good again!
For clarity here is a flow diagram: Whole house carbon filter-> RO carbon pre-filter-> RO membrane-> storage tank(s)-> RO carbon post-filter-> TDS "in" probe-> DI filter resin-> TDS "out" probe-> faucet. You can tee the line off the faucet and hook it up to your refrigerator's ice maker, aquarium auto top off system, etc."
