A drop of the good stuff

Alison Campbell of Living Water Ecosystems argues that rainwater is a precious resource that we should be taking much better care of. Problem is, that when it comes to drinking rain there is no protocol to guide us how it can be done safely.

Drinking rainwater might seem simple. In arid lands and on small islands rain is the main source of drinking water – possibly the only one at certain times of year. In these places water is precious – to waste any that can safely be drunk would be foolhardy.

But in the UK, there is precious little guidance on drinking rainwater. Most of us believe clean water is plentiful enough to flush down the lavatory without a second thought.

So much water falls from the sky in Britain that to collect it at home may seem foolish, faddish – something done mainly by sandal-wearing hippies and middle-class liberals.

Health hazards

In some tropical countries with high seasonal rainfall, insufficient clean groundwater can mean health hazards for many people, especially children. In such places properly stored rainwater could safely be drunk, but local people don’t do so because it is not traditional.

Drinking the rain is just as outlandish in the UK. After all, this is a country blessed with an abundance of clean water – or is it? With the coming of climate change, we can no longer count on water being in the right place at the right time.

Even a cursory review of the past decade should ring warning bells. Every year there is a worrying water shortage somewhere in Britain.

If we save our rainwater we will be less vulnerable. Just as planners, architects and engineers now need to consider where the river will flow when it is in spate, we need to think about how to make the best use of the rain. At the moment, most of it goes down the drain.

Rainwater is now being harvested from many industrial, commercial and council premises as part of a wider surface-water management strategy. It is collected from roofs and conveyed to an on-site storage tank, from where it can be piped into the factory for use as process water, or used for grey-water purposes, such as lavatory-flushing, laundry, irrigation and vehicle washing. However, this rainwater is rarely used for drinking.

In the UK, it is the responsibility of the Environmental Health Department of Local Authorities (EHDLA) to ensure drinking water is safe. Most Britons are connected to mains water, but there are people who live in rural areas of England, Scotland and Wales, and on some islands, who rely on a private water supply. Water authorities have gone to considerable trouble and expense to eliminate the need for private water supplies, but there are still around half a million people who live in areas too remote for a mains water connection.

Non-mains water can come from a variety of sources, such as springs, boreholes, wells, lochs and streams. Such water can, in principle, be contaminated by a wide range of substances.

When somebody proposes to drink from a non-mains supply, the local authority must appoint an inspector to examine the water supply itself, and the site from which it comes.

A suite of laboratory tests must be carried out, at a cost that can exceed £600, to determine whether the water can safely be drunk.

So far, no government or local authority in the UK appears to have seriously considered drinking rainwater. Yet the rain that falls in most areas is some of the cleanest water in the country.

Rain is just water molecules that have been evaporated by sunlight from the sea and land and condensed into clouds. Precipitation in or downwind of industrial zones may become contaminated by substances discharged by flues, but over large regions of the UK – especially the remote ones where people need to use a private water supply – it is likely to be very clean.

Toxic substances

It is the collection of the rainwater that can render it impure. Once the rain falls onto a roof, it may land on bird or rodent faeces.

In industrial areas, or close to farms, a variety of soluble substances (hydrocarbons, chemicals, fertilisers, manure) may be on the roof.

The tank in which the water is stored may not be properly sited, sealed and lined with a material approved for contact with drinking water.

Most of the impurities that can enter rainwater are easily excluded. Allowing rainwater-for-drinking facilities only where roofs are unlikely to be contaminated by toxic substances minimises that hazard.

Installing leaf filters and rejecting the first roof runoff will reduce the likelihood of contamination by faeces and gutter contents. Filtration of the rainwater with the correct porosities will remove most of the remaining impurities.

Sterilisation of the collected water with ultraviolet light immediately before drinking will eliminate any harmful organisms that may be present.

Possibly the most troublesome aspect is ensuring that the collection system is properly maintained.

The Private Water Supplies Regulations 1991 cover all non-mains drinking water in England and Wales. New legislation will come into force in 2009.

In Scotland the Private Water Supplies (Scotland) Regulations 2006 apply. Rainwater is not mentioned – it is assumed the water will be drawn from a ground source, with all that that implies. Under this legislation, the 40-odd laboratory tests required for assessment of ground water must also be performed on rainwater.

There is no regulation or guidance specifically covering rainwater, which is likely to be clean and relatively easy to make safe for drinking.

Such a document would be useful. It would describe best practice from collection on the roof to consumption, covering site suitability, selection of correct materials, rejection of the first water collected, filtration, storage, pumping, sterilisation, and cleaning/maintenance of the system.

The final stage of preparing rainwater for drinking is removal of any harmful organisms that may be present. There are various means of achieving this, but one of the simplest and most effective is sterilisation by ultraviolet light. A number of companies supply such apparatus, which is inexpensive, compact, easy to install.

What would allow us to drink rainwater safely in Britain?

Private water supplies are already covered by substantial documents in England/Wales and Scotland, but in these it is assumed that the water comes from the ground, with its potentially far more diverse and dangerous sources of contamination. What is needed is a protocol specific to rainwater.

Much progress along these lines has been made in Australia, large parts of which have experienced extreme drought in recent years. Australia’s Environmental Health Council Secretariat has produced a valuable document, Guidance on Use of Rainwater Tanks (2004; ISBN 0 642 82443 6), covering all aspects of rainwater collection, storage and safe consumption.

In South Australia, stored rain is the main source of drinking water in 36% of households. Studies there have shown no significant difference in the rate of disease between homes drinking rainwater and those drinking mains water.

The authorities in Scotland, England and Wales need to examine current legislation.

Alison Campbell is with Living Water Ecosystems.

T: 01383 415215

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