Drinking Filtered Water

I would think the majority of new builds in the UK are now fitted with rainwater harvesting. It saves money on the water bills, beats the hosepipe ban for garden watering and helps the home builder achieve Level 3 or 4 of the Code for Sustainable Homes which most councils need before giving planning permission.

If you've stored all this rain water, then why not drink it and bathe in it?

In many countries they do but, in the UK it is deemed non-potable.

However, I would like to advise that a determined UK homeowner can get the okay to use rainwater as potable water. In practice, it is vital to get water tested if the users or authorities want to be certain of its quality. There are testing companies all over Britain and one can identify them locally when required.

The UK Government's requirements are at http://www.opsi.gov.uk/SI/si2000/20003184.htm. It's quite a read.

The World Health Organisation has its say at :

http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/index.html.

The majority of council inspectors will require test results and a supplier's confirmation that the equipment will be able to deal with whatever may be polluting the water. The most common pollutants and their remedies are as follows:

1) Bacteria. Bird droppings and the bacteria these carry is the most common pollutant of rainwater from the roof of a building. Ultra-violet filtration kills bacteria, but remember that the filter must be turned on 24/7 and there must be a way of warning the users that a bulb is failing or has failed. Double bulb UV filters are available, as are ones with suitable alarms. A cartridge filter prior to the UV filter ensures that bacteria does not get through the UV filter hiding behind a particle; that's what authorities might be concerned about. If the rainwater has been filtered and stored in an underground tank with rodent protection, calming device at the input and floating intake to the pump, then a second filter in line with the UV filter is not required because the water will be particle free (as with the Carat systems).

2) Chemicals. If the building is in the lea of an industrial zone then testing might show that there is a level of chemicals in the water. A carbon filter is necessary to absorb such chemicals.

3) Heavy metals, nitrates and nitrites. If tests show a presence of heavy metals, then redox alloy cartridges are needed.

4) Reverse osmosis removes everything. If you need only a small amount of high quality drinking water then a reverse osmosis plant can supply glass-fulls with everything removed (and that includes the taste).

We know of nobody who extensively recommends the installation of equipment for adding chemicals to rainwater, but it's an option.

The bulk of tests in the UK show the presence of minute quantities of bacteria (as would spring or well water) for which Ultra-Violet filtration is ideal. Our recommendation is to install the Carat tank with a UV filter, then have a test done after commissioning and the first couple of rainfalls.