Where drinking water comes from

There are three main sources of fresh water available to us;

Rain

All of the fresh water on the planet will at one time have fallen from the sky.
Whether it flows away in rivers, sinks into underground aquifers or evaporates it inevitably returns to the Earth’s surface as rain.

Surface water

Rivers, streams, ponds and lakes; All of these are fed by precipitation and as such are at the mercy of local climatic conditions.

Ground water

Springs, deep wells and shallow wells: Like the lakes and rivers these underground sources were created by rainfall.
It may take thousands of years to create a significant underground reservoir but human activity has been shown to deplete these reserves very quickly.

“Safe” Drinking Water

To be considered suitable for human consumption water has to be free from a variety of contaminants;

These include salts, minerals, heavy metals, biological organisms (including pathogens, parasites and algae) and simple dirt.
It also needs to be ph balanced, that means neither too acidic nor too alkaline. The cells in our body are very slightly acidic (around ph 6.8) the fluids around them including blood and plasma are mildly alkali (closer to ph 7.2).
Our bodies can respond quite badly to changes in this balance so maintaining a neutral ph of 7 in our drinking water is essential.

Fortunately the action of evaporation, condensation and precipitation remove most of these substances but do generally leave a degree of acidity gained from pollutants in the atmosphere.

So if we obtain water from rain it requires minimal treatment to make it relatively safe.

Once on the ground this changes rapidly;

Rivers and lakes are perfect environments for many of the organisms which threaten human life; water from these sources requires extensive purification before we can consider it safe.

Once water has percolated through the ground into aquifers the natural filtration process, the low temperature and lack of sunlight remove threats of a biological nature and leaves water as safe as it can reasonably be found in nature.
It does however acquire minerals during its passage through the ground and this can give rise to unsuitable ph levels and discoloration.
Whilst this is rarely a serious health risk some treatment may be required to remedy this issue.

For this reason underground water sources are the ones preferred and most exploited by people today.
They are also the resources under the greatest pressure from depletion and contamination,
largely because they are hidden from view and rarely examined in detail.

To call any water “safe” for public consumption in Europe it has to meet strict guidelines and be tested regularly to ensure compliance.

For this reason we are unable to consider rainwater as “safe” because it has not been through this process!
In reality no one is likely to become ill from dinking rainwater that is freshly fallen but for reasons of caution and compliance with legislation we must consider it as a possible risk to health.
Like any other source of water once adequately treated and properly stored it is fine for all human uses.

There are numerous pieces of legislation pertaining to water standards and supply but for the Irish people the principal ones to consult are:

The Water Services Act 2007

Drinking Water Regulations S.I.No. 278 of 2007

These are amended regularly but the basic ideas contained in these acts form the structure which all persons involved in water supply or services must adhere to.

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