White goods are major sources of domestic water consumption (a typical washing machine accounts for 14% of the average Hertfordshire household’s water use) and can also be significant consumers when used in offices or other building types (e.g. in catering or service areas).
Water efficient white goods can achieve major water savings. Highly water efficient washing machines currently use less than 50 litres of water per wash, which is less than half the amount used by a machine that is 10 years old. Similarly, highly water efficient dishwashers use less than half the water required to wash the same dishes by hand.
Where white goods are included within a development, highly efficient models (e.g. A rated) can deliver water bill reductions of £20-£40 a year together with lower energy bills. Where white goods are not included, developers can encourage occupiers to purchase suitable products by providing information (in buyer or tenant packs) on the benefits of using A-rated products.
It is possible to buy A-rated washing machines and dishwashers for comparable prices to non A-rated products. However, it is worth noting the specific water consumption of a product in addition to its rating because some products will be more efficient than others even with the same rating.
Energy rating label for a washing machine
The water and energy consumption of white goods are directly correlated because most energy consumption is related to water heating or pumping. In many cases the most water efficient product is also the most technically advanced product and also offers performance, noise and other benefits.
Landscaping and irrigation
Watering of gardens and landscaped areas accounts for 5.6% of total water use in Hertfordshire and in summer can amount to up to 50% of total water use. Water-efficient gardening could significantly reduce the pressures on Hertfordshire's water supply.
Measures and techniques
The techniques and approaches suggested below can be instigated in a new area of landscaping or in existing gardens.
- Use healthy soil with plenty of organic matter to retain moisture.
- Choose plants for drought tolerance, compatibility with the soil and planting position.
- Plant new shrubs and trees through plastic to retain moisture, loose mulches can be used around established plants.
- Low-maintenance alternatives to planted areas include gravel and decking.
- Let the grass grow longer in lawns, this reduces the need for watering.
- Water in the early morning or late evening to prevent water loss from evaporation.
- A Mediterranean-style garden needs far less water to maintain. The plants suitable for such a garden are used to hot and dry conditions and are adapted to poor, free-draining soils.
- Drip irrigation can save water in large planting schemes. Porous hoses irrigate by "weeping" water on to or below the ground surface. Technically, these are unattended watering devices and therefore need to be on a metered water supply.
For most buildings, the water drawn from taps is a large proportion of the total consumption (e.g. 30% in homes and 35% in offices). Modern water efficient taps use up to 80% less water than the pillar taps installed historically. Water efficient taps can be bought as a new unit and existing taps can be retrofitted. Most water efficient taps are very low cost and present rapid paybacks.
There are three types of simple water efficient tap, these are:
- Aaerated taps.
- Flow regulated taps.
- Auto stop taps (e.g. percussion or push button).
Aerators and flow regulators come in varying sizes and flow rates and restrict the flow of the tap water whilst not appearing to do so. Percussion taps release a limited amount of water per use and close automatically. Some flow regulators are designed specifically for taps and are usually fitted in either the tail or the seat of the tap. In addition to restricting water flow and reducing water bills, regulators can last longer than conventional tap washers and can reduce maintenance costs.
In specialist environments such as healthcare, more complex taps such as proximity detection taps can be preferable, as the user does not need to touch the tap before or after washing hands.
In Hertfordshire approximately 12% of household water is used at the hand basin. However, spray taps are not always desirable in homes as they increase the time it takes to fill the basin.
Water saving inserts/cartridges can address this problem. These devices can be fitted to most taps with a round outlet hole or standard metric thread and to single lever mixer taps. At low flows the devices spray enough water for washing hands or rinsing toothbrushes. As the flow is increased, the device opens up to allow unrestricted flow.
Taps with a standard outlet thread can easily be fitted with spray heads and many round outlets can also be adapted. Metric fittings accommodate a greater number of water saving devices such as sprays and aerators. The air gap between the tap discharge outlet and "spillover" level of the washbasin must be sufficient to prevent a backflow of contamination into the pipework.
Typically, every person uses 40 litres of water per day for toilet flushing. This is more than 20% of domestic water use. The most efficient WCs can reduce daily water use to less than 20 litres. Vacuum and waterless toilets reduce consumption even further. Water efficient toilets cost no more, or only a nominal amount more, than standard toilets. They are applicable to both new projects and refurbishments. Payback periods are favourable.
The 1999 Water Supply (Water Fittings) Regulations require that new WC flushes are no greater than 6 litres. Dual-flush cisterns are permitted if the method of operation is clear. The smaller flush should be no more than two thirds of the full flush. Low flush siphon toilets are also available and recommended, as they are less susceptible to leaks than dual flush valve toilets.
Waterless toilets are very effective in remote areas that do not have a mains water supply (e.g. country parks). They are similar in cost to conventional on-site drainage for rural new-build projects.
The most common form of waterless toilet is the composting toilet. These toilets compost waste into a fertiliser product. They range in size from a large box that fits in a bathroom to larger units installed underground.
Smaller models use heaters and raking or tumbling mechanisms to accelerate decomposition, while larger models rely on natural processes, sometimes with the help of tiger worms and the addition of fibrous material such as shredded cardboard or sawdust. The energy used by the heaters in small units offsets some of the environmental benefits of water saving.
Waterless toilets have no drains to block and no sewage sludge is generated. Dry toilets are also immune to freezing, which is a consideration for remote sites and outdoor toilets without power for frost protection.
Dual-flush and low-flush toilets can cut total water use in the home by 20%.
Vacuum toilets can be economic for larger projects, particularly where conventional gravity drainage is problematic, e.g. in historic buildings. Vacuum toilets have a typical 1.2 litre flush, which reduces typical toilet flushing consumption by about 90%.
Cistern displacement devices
Where WC replacement is not an option, the flush volume of older toilets can be reduced by displacing water in the cistern and reducing each flush by that amount (usually 1 litre).
Retrofit variable flush mechanisms
Variable flush mechanisms can also be fitted to older toilets. These typically reduce water consumption more than cistern displacement devices.
Urinals typically use less water than WCs, but can still waste a lot of water if incorrectly installed. Typically, urinals account for about 20% of office water use. Water efficient urinals are very affordable to install in both new projects and refurbishments and their maintenance costs are typically less than those for standard urinals. Payback periods are often very favourable. Waterless urinals are a recent development that use no water other than for cleaning.
Without controls urinals can use four times as much water as is necessary. Urinals can be controlled according to time (e.g. set to operate during working hours), movement or mechanical movement triggers (e.g. a door opening, a tap being turned on or a person entering the washroom).
For larger washrooms it is important to use separate controls for each urinal, to prevent all the bowls being flushed from a single use. Simply installing urinal controls is not sufficient, systems need to be commissioned and periodically tested to ensure they are operating as intended.
A range of urinals use no water. Some systems are supplied as a complete unit whilst others can be fitted to standard bowls and troughs. There are a variety of forms of waterless urinal:
- Those with disposable chemical traps
- Those with permeable one-way valves that seal the urinal opening
- Those that create a negative air pressure to take odour from the washroom
Waterless urinals are simple to install and have no complex controls or plumbing exposed to potential damage or vandalism. Waterless urinals also address scale, odour and flooding problems. Odour is often incorrectly perceived to be a problem with waterless urinals, so most manufacturers offer a scented block, stick or pad.
Waterless urinals typically require little maintenance and are increasingly being used in public facilities such as football stadiums and schools, and even in fast food restaurants.
Water saving showers
Bathing accounts for 25% of the average Hertfordshire household’s water use. Showers typically use about a third of the water and energy of an ordinary bath. However, power showers have higher flow rates and can consume as much water as a bath. Low flow showers cost no more than standard showers. Showers with a flow rate at the upper end of the 4-9 litre per minute range are preferred by users.
The choice of mixer valve affects the water use for showering. Simple hot and cold tap controls require both taps to be adjusted (often for a period of time) before the correct temperature is found. Single level taps and thermostatic mixers typically enable the user to waste less water.
Shower flow rates
Shower flow rates can vary significantly. Water efficient showerheads work in the same way as an aerated tap, by creating finer drops or by introducing air. Water efficient showers typically work at a flow rate of 4-9 litres per minute but have the feel of a power shower. Water-saver showerheads and restrictors are not appropriate for use with electrically heated showers without the consent of the manufacturer.
A shower uses 1/3 of the water of a bath, but power showers can use more water than a bath in less than 5 minutes.