1. Understand the chemical composition of your water before buying a residential water filter, that is, the degree of water pollution. For this purpose, carry out laboratory water quality analysis on your drinking water. This will include general water testing, including the identification of total coliforms, nitrates / nitrites, pH, total dissolved solids (TDS), fluorides, organic carbon pollutants (pesticides, industrial pollution, etc.). The mechanic who repairs the water filter in your area can be a good source of the main information you are looking for. This will help you decide whether you want a water filter to remove dissolved minerals from the water, a purifier to kill bacteria, or a water filter with both functions.
2. Decide whether you want the whole house's water system or just a drinking tap water filter.
3. Many brands shortlist in the market. Understand product standards. National Health Foundation (NSF), water quality association (WQA), food and Drug Administration (FDA) and other well-known agencies have certified the water filters, which is the safety sign of consumers.
4.The best quality of water filters and membranes are expensive. You should compare the functions and prices of existing purifiers in the market. Before finalizing, it is important to consider the maintenance cost of the machine.
5.Clear the following questions：
Is the product certified by NSF, WQA and FDA?
How often does the sediment water filter / membrane need to be cleaned or replaced?
What is the warranty period of machine parts? How much free service does the company provide?
If it is a reverse osmosis filter, what is the filtration speed? (it is recommended to purchase high-speed water filter to ensure good flow of water).