With water metering looming, Dublin consumers hastily dropped their consumption of water late last year, and the numbers of people seeking water conservation advice rose. With water charges now capped till 2019, the numbers enquiring about water-saving ideas has dropped off considerably.

Eamon Kearney of Celuplast in Baldoyle, Dublin, says the company held an information weekend before the fixed charges were announced "and, pardon the pun, but there was a deluge of people in to us".

Celuplast brought in 200 rainwater- harvesting units from the United States and has sold half of them but demand has dropped by half since fixed charges came in. For now, the "urgent interest about a year ago has dissipated", says Kearney.

“Making savings is about reducing the volume of cleaned water provided in the first place and also reducing the volume of dirty water that has to be treated afterwards,” according to one civil engineer.

In Britain, consumers can get a rebate on their water charges if they divert rainwater from their property into a “soakaway” instead of paying for their water company to treat it.

Asked if it has any plans to offer a similar reduction to consumers here Irish Water says that "there are no plans in place to introduce this, as the model in Ireland is based on an equivalent cost being charged for water in as for water out. Therefore there is no charge for rainwater as it will not enter the water supply in the property."

But rainwater harvesting could make real economic sense soon as some 50 per cent of what we use doesn’t need to be drinkable. It’s estimated that we currently flush away 30 per cent of our water, use another 13 per cent for washing clothes and 7 per cent to clean cars. Rainwater harvesting means the free water falling on the roof is channelled via the existing gutters and down pipe to a filter which removes leaf litter and other debris before diverting the water into a storage tank.

The resulting water can then be plumbed into the house for use in a utility room, downstairs toilet, watering the garden or cleaning the car.

Drinkable water is still needed for cooking, dishwashing and washing ourselves, although some systems provide further filtering using, for instance, ultraviolet (UV) light to yield water that can be used for washing. It’s also possible to put in a reverse osmosis system that provides water suitable for human consumption, according to Garrett May of Harvesting Water Works.

Enlightened self-builders

Charles Burns, director of water at Kingspan, says there has not been mass adoption of rainwater harvesting equipment in new builds by developers but a "substantial quantity" have been sold to self-builders – which he calls "the most enlightened market".

Kingspan has lobbied successive ministers for the environment since John Gormley was in office in 2007-2011 to put rainwater harvesting into the building regulations. Last year the then minister for the environment, Phil Hogan, was reported as saying rainwater harvesting would be a requirement of planning permission in the review of building regulations he hoped would be in place this year. All buildings, including apartments, were to be covered.

“There’s huge pressure on the east coast of Ireland in relation to water,” he said. “If people are being charged, they have to be incentivised to reduce bills,” he added. This week, however, the Department of the Environment said: “At the time the minister was expressing what he was thinking of in the context of the introduction of domestic water charges. The installation of rainwater-harvesting systems is a matter for individual homeowners.”

There is a variety of systems on the market. A “deep-fit” system, placed underground at building stage and integrated into the property’s plumbing, uses a tank sized according to the area of the roof, says Burns. Kingspan sells a gravity-fed system which works even with a power failure. Like other systems, it’s backed up by the mains supply when the collected rain dips below a certain point.

Tony Murphy of tanks.ie in Waterford sells a variety of underground systems, including the Envireau system supplied by Kingspan and a range of above-ground tanks ranging in capacity from 800 to 10,000 litres. The cost of installing a rainwater-harvesting system ranges from €700 to €3,000, plus VAT at 23 per cent.

Celuplast is still selling about one Guardian above-ground system a week. It costs €1,604, including VAT, and includes two tanks holding 540 litres. The slimline tanks are particularly neat, hanging only seven inches off a wall, and can be integrated into a boundary fence.

Celuplast also has an 800-litre tank system for €1,527 including VAT.

Cathal Keane of JFC Manufacturing in Tuam says new estates are now including rainwater harvesting in their specifications. JFC sells a Graf system with a UV filter, which provides water that can be used for bathroom washing.

To bring collected water up to drinking quality, Galway Water Solutions sells an entry-level system of reverse osmosis, sediment filtration and UV light for €1,200 to €1,400.

There’s also a range of smaller-scale water-saving devices such as aerating shower heads and flow-restricting inserts for taps. They can be found in stores such as Chadwicks, Woodies and Heiton Buckley.

Colm Griffin of purchase.ie in Kerry has a useful "shower head water-saving challenge" video, demonstrating a timed one- litre fill by various shower heads which consumers can try out to check if their shower head could do with upgrading. His video shows shower heads ranging in use from 12 to six litres per minute, the winner being the Aguaflux at €24.95. The cost in showering per year ranged in the test from €85.50 to €171, depending on the shower head used.

Instant hot water Griffin

also sells instant-hot-water taps for kitchen or bathroom (to save wasting water as one runs the tap to reach a decent water temperature) at €197.95. For €99.95, purchase.ie will supply a water-saving kit comprising a 200-litre water butt, two tap aerators, the Aguaflux showerhead, shower timer and a bag to displace water in the cistern, reducing the water used in a flush.

As well as dual-flush cisterns there are devices on the market which anyone can retrofit into an existing cistern, such as the Ecobeta for €28.50. Even cheaper is the Mecon water-saving button invented by two Irish men at meconwml.com, for €20 plus €3 post and packing.

(This writer’s home has had two Mecon buttons installed for the past 10 years.)

Mecon has been able to sell its button into Britain as well as numerous Irish schools, where 85 per cent of water supplied is used for flushing toilets and where metering has been in place for some time. It can be fitted in five minutes and saves 60 per cent of water, as the user pushes a button to stop the flush as required.