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 has been treated by the government, it probably does not have bacteria in it. However, the water still has a lot of junk in it 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 $35, and the filter housing, bracket, screws, and wrench cost $70. (Remember, this would merely give you filtered water, not reverse osmosis water.)
In addition to the sediment filter, you could also add a carbon filter to remove chlorine and organic chemicals from your water. The carbon filter can be installed after the whole house sediment filter. The particular filter we recommend is called a Matrikx CTO/2 filter. It is a 10 micron filter which is good for 26,000 gallons of chlorinated water. Since the average person uses 70 gallons of water per day, it should be changed every 6 months for a two-person household, every 4 months for a three-person houshold, and every 3 months for a four-person household. The filter is 20" long and 4.5" in diameter. It costs $70, and the filter housing, bracket, and screws cost $70. (Remember, this still does not give you 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" tubes to more than one sink.)
If you still want a whole-house reverse osmosis system, please click here.