The quality of water that one uses in their garden is nearly as important as the nutrients themselves. Water is the vector by which the macro and micronutrients are delivered to your plant and as a result of this intimate relationship your water quality will dramatically influence the effectiveness of the nutrients you are using. Things to consider when analyzing your water quality are: EC, pH, chlorine or chloramine levels, excessive carbonates and bicarbonates levels, biological pathogens, petrochemical contamination, and dissolved oxygen levels just to name a few. Without an understanding of what is in your water it is difficult to determine the type of filter best suited for your application. You will also need to determine what your peak demand usage will be and whether or not you intend on constructing or purchasing a water storage reservoir. R.O. systems are the most popular choice with many models costing less than 300 dollars, however these versions generally produce less volume than their higher priced commercial volume comparatives. If your peak demand is 200 gallons a day but it is only on the day you change your reservoirs than a 100 gallon per day model with storage would be more than sufficient. If you don’t have room for storage or if you want R.O. water on demand than a larger commercial style assembly would likely be a better choice.