Under normal circumstances, we do not recommend a whole-house reverse osmosis system. This is because one doesn't normally need water of such high purity for uses such as bathing, flushing the toilet, cleaning, etc. In addition, if you remove most of the Total Dissolved Solids ("TDS") from water -- as reverse osmosis does -- the water can slowly dissolve copper pipes. Although there are ways around this (such as adding a phosphate cartridge or increasing the TDS), this would make your water less pure.
If your water comes from a well, it probably has some bacteria in it. However, for most people, their immune system can handle a small amount of bacteria. If you are drinking the water now and merely want purer water, a less expensive way to go would be to merely use a sediment filter for your general house water. This filter will screen out most of the junk in the water which can coat your water pipes and damage your washer. If you want to screen out this junk, we recommend a sediment filter which can be installed in your water pipe at the point where it enters your house. The particular filter we recommend is called a 20" long (4.5" diameter) Dual Gradient Density filter. The outer layers of this filter screen out particles over 50 microns in size, and the inner layers screen out particles over 5 microns in size. The filter costs $30, and the filter housing, bracket, screws, and wrench cost $80. (Remember, this would merely give you filtered water, not reverse osmosis water.)
For drinking, cooking, and ice cubes, you could then install a regular reverse osmosis system under your sink or in your basement. (You can run 1/4" tubing to more than one sink.) This will screen out bacteria, but if the membrane ever fails, bacteria could get through. As an extra safeguard, you could install an ultraviolet light.
If you still want a whole-house reverse osmosis system, please click here.