Water Management Planning Guidance for Construction Projects

Water Management Planning Guidance for Construction Projects

 

head Efficient-welfare-plant-and-equipment

There are many ways in which you can ensure that welfare facilities and processes which use water on site are as efficient as possible. A checklist is provided in the accompanying template document.

Welfare activities have been shown through a series of water audits on constructions sites to be one of the largest users of water as they are in place from site commencement through to the end of site operations. Information on these audits can be found at

Greening the Industry: Water Subgroup

Welfare facilities

If site cabins are to be procured, arrangements should be made for these to be water efficient. Where existing facilities are to be used for the duration of a project, consideration should be given to improving the efficiency of these to reduce water use.

Site accommodation can comprise the following types of water use:

  • Toilets;
  • wash hand basins;
  • urinal flush;
  • showers;
  • catering and food preparation; and sometimes
  • boot washing.

Site accommodation should use plumbed in water dispensers once mains water is connected (albeit more of a cost and carbon saving than a water saving).

It is recommended that the Water Technology List (WTL) is consulted prior to the purchase of toilets. The WTL not only ensures products are of a certain quality, but allows companies to reclaim 100% first year capital allowances through the Enhanced Capital Allowance (ECA) Scheme.

http://wtl.defra.gov.uk/

Wash hand basins

Generally wash hand basins on site have cold taps that feed directly from mains water, controlled by a turn mechanism. On some occasions percussion (push button) systems are installed. The most common water efficiency problems with this sort of system are:

  • Flow from cold taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good practice).
  • Potential for taps to be left running for extended period (i.e. no auto-isolation of flow) for taps without percussion mechanism.
  • Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

The most practical methods by which basin taps can be ensured to be water efficient on site, without compromising the potential performance of the appliance are:

  • Installing taps with percussion mechanism (push button) with appropriate calibration (5 seconds is suggested).
  • The use of motion sensors.
  • Installing taps with efficient flow patterns e.g. spray taps or aerated taps.

Although pressure reducing valves (PRV) installed on site accommodation can result in reduced flow rates through taps, and hence water efficiency, without a full understanding of the potential siting of the accommodation and water pressure, it is not possible to tell if a PRV would be appropriate.

Offering variable PRVs in accessible location is an option, although these might not be adjusted once on-site and hence savings might not be realised.

Toilets

All new toilets must now have a flushing volume of 6 litres or less to comply with Water Supply (Water Fittings) Regulations 1999. However, a number of more efficient options are now available on the market including toilets that flush a maximum of 4.5 litres.

Dual flush toilets are another option, where the ‘half’ flush (typically 4 litres or less) is suitable for liquid flushes. If dual flush toilets are installed then there should be clear labelling as to how the flush mechanism is operated to prevent occurrences of ‘double flushing’.

Urinals

Good practice involves installing a device to control the flushing based on how often the urinal is used. There are a number of options to achieve this, but good practice for the construction sector would normally involve the use of low maintenance hydraulic valves.

A hydraulic valve can be fitted to the inlet pipework of the urinal system, and does not require power to operate. When the inlet water pressure decreases temporarily through water being used elsewhere in the washroom (e.g. toilet flushing or hand washing), the diaphragm-operated valve opens and allows a pre-set volume of water to pass into the urinal cistern. When the cistern is full, the auto-siphon will discharge and flush the urinal. When the washroom is not being used, the pressure remains unchanged and the valve remains closed. Thus, the cistern should not use water out with working hours. It may also reduce water consumption throughout the day, depending on occupancy levels

Waterless urinals are another option to consider.

Showers

If a shower is to be installed in site accommodation then consideration of the flow rate through the device should be made. A flow rate of 6 to 8 litres per minute is considered efficient.

Typically, electric showers are likely to be installed. It is important to note that retrofitting of alternative shower heads is not recommended for electric showers. A low to moderate power electric shower will typically offer efficient flow rates.

Canteens and food preparation

Trigger-control to ensure auto-isolation of flow should be fitted to sink taps. This will prevent taps being left running when not being used.

Plant and equipment

All processes on site that use water will inevitably involve some plant or equipment. Water using activities should already have been identified. The water use of the plant & equipment should be taken into account in the procurement process.

Examples of water efficient technologies can be found in the water audit report available at

http://www.wrap.org.uk/content/water-efficiency-construction

along with a summary of ten very simple tips for sites to ensure efficiency.

In identifying suitable equipment, the water source being used will need to be accounted for – for instance if using directly abstracted water for dust suppression it may not be possible to use misting techniques due to health risks.

Maintenance

Welfare facilities should require relatively little on-going maintenance to ensure low water use. Basic checks can be carried out to ensure facilities are operating as designed through:

  • Checking that taps are not dripping
  • Checking that percussion taps do not run for longer than necessary
  • Ensuring the sensor driven taps and/or urinals are working correctly
  • Ensuring toilets are not leaking through the overflow or valves

Basic awareness raising of these with site staff, and implementation of a reporting system for any problems that are identified should keep water use from welfare as low as possible (see site behaviours and training section)

Plant and equipment will each have individual maintenance requirements. The instruction provided with the equipment or from the hire company should be followed to ensure efficient use.