If you want to filter 100% of your water correctly, we suggest an in-line system like the Reverse Osmosis one. However, if the thought of £300 for clean water is too hard to swallow we have an alternative worth considering.
The Fileder Budget Water Filter is our answer. It uses two filters; one for sediments like rust, the other (carbon) is used for filtering heavy metals like lead and gases like chlorine.
The Ametek filters supplied come in blue slim line housings with a half inch port that sit under the sink. To connect to the water system you simply cut the cold water pipe, connect the compression connectors (not supplied) and screw both ends back into the cut pipe. You may need a bracket and housing spanner, which any plumber's merchants can supply.
The complete system costs under £80 (including VAT). The component costs are £29.99 for each housing, £4.70 for the sediment filter and £15.30 for the 20-micron carbon one. You will need to replace the filters after every 1500 gallons of water - typically every 6 months.
Although there are many different brands of budget water filter systems on the market, in our view, this is the best value-for-money option. Other darkroom suppliers charge more than this just for ONE housing!