Several weeks of rain needed to replenish Irish Water supplies

Irish Water analysis shows spike in domestic usage during days with sunny weather

Water conservation orders - known as a hosepipe ban - were first introduced in Dublin during the summer of 2018, and later extended to much of Leinster and Munster.  Photograph: iStock

Water conservation orders - known as a hosepipe ban - were first introduced in Dublin during the summer of 2018, and later extended to much of Leinster and Munster. Photograph: iStock

 

Irish Water would need several weeks of rainfall to replenish water supplies the national utility has said, as the greater Dublin region faces the prospect of an imminent hosepipe ban.

The recent period of dry, sunny weather and increased demand has led to pressure on the water supply for Dublin and surrounding counties, with a water conservation order under consideration.

Irish Water would need “a minimum accumulation of 100mm rainfall spread over a number of weeks and a return to normal precipitation levels thereafter” to replenish reservoir supplies, a spokeswoman said.

Forecasts from Met Éireann show the country could get between 20-30mm of rainfall over the next ten days.

Meteorologist Elizabeth Coleman said the eastern part of the country could see rain over the weekend and into next week, however that was uncertain and “subject to change” over the coming days.

Water conservation orders - known as a hosepipe ban - were first introduced in Dublin during the summer of 2018, and later extended to much of Leinster and Munster.

Irish Water has seen a 20 per cent increase in domestic water usage during the coronavirus lockdown, in part due to associated increases in handwashing.

Some 16 of its water supplies are currently classified as at “drought” level, while a further 38 are “pending drought.” As a result the national water utility has said the introduction of a hosepipe ban to reduce demand was highly likely in the coming weeks.

The hosepipe ban would prohibit households from unnecessary water use, such as watering gardens, filling paddling pools, or washing cars or boats.

Internal Irish Water analysis, provided to The Irish Times, shows water usage increases significantly during periods of warm weather. This means a long period of rainfall both replenishes water levels and lowers demand on the system.

The greater Dublin region used 585 million litres of water on 11th April, a day without rain when temperatures hit over 18 degrees. That dropped to 550 million litres of water the next day, when temperatures were around 10 degrees with rain showers.

On May 20th, Dublin saw temperatures of 22 degrees, with sunshine and no rain, resulting in a spike in water usage to 600 million litres. Two days later on a windy day with rain showers demand fell to 550 million litres, according to figures from Irish Water.

This spring has been the driest on record in Leinster since Met Éireann’s digital records began around 70 years ago.

Since early March seven weather stations have experienced an “absolute drought,” which is 15 consecutive days without rain.

Drought-like conditions have been most apparent in Dublin where the Phoenix Park weather station had 42 days from March 18th to April 28th, in which just 5.8mm of rain fell.

Similarly the weather station recorded just 8.3mm of rain during the whole of last month, the driest May since 1991. The past week has also seen temperatures reach 27 degrees in parts of the country.