Rainfall in Dublin welcomed as boost to reservoir levels

Rainfall in Dublin on Tuesday has been welcomed by Irish Water which says more rain is now needed to avert night-time restrictions on supplies to households.

Managing director of Irish Water Gerry Grant warned of a threat of drought in the Dublin region because of the unusually dry autumn conditions.

Water levels at Pollaphuca in the foothills of the Dublin mountains are at the lower end of the storage range, at a point where the water authority said a range of options would have to be considered if there was not more rain.

Water levels tend to be low at this time of year after the summer. This allows for storage of winter storm water rolling off the Wicklow hills which is “a critical flood control measure for the city”, Irish Water said.

But the authority warned that if the water in Pollaphuca falls significantly below current levels “the options range from minor night-time restrictions with minimal customer impact to more extensive restrictions and, in very extreme cases, water rationing”.

Supply vs demand

Water restrictions in normally wet winter months are not unknown in recent years and, in December 2010, Dublin City Council said demand was exceeding supply by about two million litres a day.

In October 2014, when residents in the Dublin water region – which takes in parts of Wicklow and Kildare – thought they were being charged for water on the basis of how much they used, consumption dropped from an average of 543 million litres a day in September to less than 524 million litres in October.

The decline in usage of nearly 20 million litres in a month was estimated to save €25,000 per day in treated water.

The Dublin region accounts for about 1.5 million people or about one-third of the State’s population.

A spokeswoman for Irish Water said the storage at Pollaphuca in coming weeks will determine any steps that need to be taken to manage water supply for the region.

Water capacity

Target storage is between 180 and 120 days’ worth, depending on the time of year. Currently water storage is trending at 120 days. While Irish Water has taken steps to maximise spare water capacity in Dublin in recent years, additional economic growth has also led to an increased demand for water.

Irish Water said the growth in demand is expected to continue but expressed the hope that as it was now November “rainfall will address the issue”.

Met Éireann said the outlook for the coming days was for showers or longer spells of rain continuing in the west and north, but mainly dry conditions in the east and south. Thursday should see fewer showers while Friday is forecast to be cloudy and breezy with rain at night. The weekend outlook is for a bright, breezy day on Saturday with some sunny spells. It should be dry and bright at first on Sunday, with sunny spells. But cloudy weather will develop as the day progresses, with a little rain possible in the afternoon.