Hello

Do you really need to filter all your water ? The stuff you use to flush the loo ? The stuff you use to wash clothes ? I have cheap little filters on the loo to trap sand and other stuff from blocking the valve. I clean it about once a year or when it is obviously blocked. I bought a 5 stage osmosis unit from BricoMart in Castellon (same DIY chain as B&Q) for €99. This does the drinking water. I have replaced the filters once in 2 years. I bought a cheap water tester off ebay. This measures suspended solids. The filtered water is always better when compared to bottled water as to suspended solids. You can always buy the bottled stuff to drink neat if you have doubts. You usually boil the water in cooking, making tea etc so the filtered stuff will be fine. I hope that helps
David