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Dublin: 19 °C Sunday 19 August, 2018
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How to retrofit your house to save water and money

Water charges are coming…so bring on the rain harvesting.

WATER WATER EVERYWHERE, and all of it going to be charged for.

What with the water charges bills being released recently and a better awareness generally about the environment, water conservation is often to the forefront of the conversation.

It might not seem necessary here in wet and rainy Ireland to be overly concerned with water preservation but, water charges aside, it is something we should all be conscious of.

Source: kohlmann.sascha

There are simple tips and tricks to preserve water such as

  • putting a brick or a full 500ml bottle of water in a toilet cistern to replace some of the water that fills the cistern – displacing/saving that much water with every flush
  • putting a basin in the shower and collecting water that way and using it to fill toilet cisterns or watering the garden
  • using a bucket instead of a hose when washing the car
  • watering your garden in the evening instead of at the hottest part of the day
  • turning off the tap when brushing your teeth
  • limiting time in the shower

You know what we’re talking about.

However, if you’re planning a proper go at some water conservation and preservation then we’ve got just the ticket for you. Rain water harvesting.

Source: Flickr - Photo Sharing!

 What is it exactly?

A rain harvesting system does exactly what it says on the tin – it harvests your rain water from gutters and sends it to a tank where it’s filtered and then used to fill toilet cisterns, garden hoses, even the washing machine, cutting down on using the mains water and thereby helping the environment and your own water bill in one fell swoop.

Toilet flushing accounts for approximately 35% of a house’s water usage, with washing machines at approximately 15%. This water is processed, drinkable water – which is effectively being flushed away. No wonder collecting rainwater and using that is a better idea.

It might not be the most glamorous of topics, but rain water harvesting is what it’s all about these days.

We spoke to Eamon Kearney at Celuplast to get the scoop.

Source: Celuplast

How does it work?

Rain falling on a 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 filter is mostly self cleaning and the tank is purpose designed to protect the quality of filtered rainwater during storage.

The mains valve kit comprises a valve, float switch and tundish to comply with water regulations.

When a service demands rainwater a pump is automatically activated by a pressure switch to draw water from the tank. The flow rate is sufficient to refill a modern toilet cistern in less than a minute and other pump models are available for heavier duty requirements. In the event that demand exceeds the availability of rainwater, a mains water valve is automatically opened to partly refill the tank.

How do you know what size system to go for?

In domestic situations, the same process prevails for smaller and larger installations. The only change will be the size and shape of the tanks needed to service the water requirements allied to the roof space available to collect the rainwater as is falls. If for example a house has a very small roof but has numerous people living in the property, it may not be possible to harvest enough water to service their non potable needs. The bigger the roof the more water becomes available.

Source: Celuplast

Average rainfall documentation is readily available for areas throughout the country which can allow householders calculate how much water that they can reasonably expect to harvest in a given year. This will also determine the size and quantity of tanks necessary to achieve an optimum harvest.

A quick rule of thumb – 1 millimetre of rain falling on 1 square metre of roof space results in 1 litre of harvested water. Therefore if a roof has an area of 100 square metres and average rainfall for that area is 800mm per annum then 100 x 800 = 80000. That means that on average there will be 80,000 litres of harvested water available to the householder for non potable uses.

By calculating water usage through washing machines, toilets and garden hoses per person living in the house we can then calculate the contribution rainwater can make to the households water usage.

Not exactly what you'll be in for, don't worry. Source: Althewebmaster

What’s the difference between grey water tanks and rain water harvesting?

Grey water is quite different from basic harvested water. It is really only used for toilet flushing and occasionally garden watering. Grey water is the water which drains from our washing machines post washing and may indeed be almost any colour. However it is always dirty. The problem with grey water is that it is unsightly and many consumers are uncomfortable with dirty water lying in their toilet bowls.

Harvested water on the other hand is clean and clear and when put through correct filtering is ideal for washing the clothes in the first place. It also contains no lime or calcium which frequently damage the inner workings of washing machines.

What are common concerns and problems for homeowners when fitting a rainwater harvesting system?

The real issue surrounding this is the distinction between potable and non potable water. Potable water is that which is supplied to our homes through the local authority water system. This water has been treated to ensure no harmful bacteria can be ingested by home occupants. Bacteria such as Cryptosporidium or Legionella can exist when water is allowed to stagnate and then reaches a certain temperature. Although these bacteria can occur in the potable water supply they normally exist in untreated water.

For this reason it is imperative that water harvested from rainfall is only used for non potable purposes i.e. non drinking water. Ideal uses for this harvested water are washing machines, toilets and garden hose usage. This can amount to as much as 60% of our household water usage.

Source: LadyDragonflyCC - );

What building regulations are there in place for new builds regarding water saving/harvesting?

Currently to my knowledge there are no regulations with regard to water harvesting on a domestic scale…Worldwide, countries reward consumers for harvesting water using proprietary systems. It will be vital that Ireland follows their lead if real understanding and cooperation is to be achieved.

Eamon Kearney’s top tips for water saving:

  • Make sure to do a full load in the dishwasher or washing machine
  • Keep clothes laundering to clothes that really need it – reduce the amount you wash
  • Chose the most economical model of dishwasher and washing machine – modern machines are incredibly efficient when it comes to water and electricity
  • Newer toilet models have dual flush modes – use that if possible otherwise ‘toilet bricks’ can be bought from the hardware store. Using something to displace the water in a cistern can result in gallons of water saved every day
  • Don’t leave water running while shaving or brushing teeth

Read: These are the cheapest places in Ireland to buy a family home

Also: These are the places where the world’s super-rich really live

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About the author:

Edel Corrigan

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