Water Conservation

Water conservation covers the measures that reduce a building's water use: efficient taps, showers, toilets and urinals; leak detection and repair; cooling tower water management; efficient irrigation; rainwater harvesting and water recycling (whose systems are covered on the specialist hydraulics page); and metering that shows where water goes. In offices and commercial buildings, cooling towers, toilets and leaks dominate use; in apartments, showers, toilets and leaks.

Labelling schemes help choose fixtures: the Water Efficiency Labelling and Standards scheme is mandatory in Australia, the Unified Water Label is used in Britain, and WaterSense is the US Environmental Protection Agency's voluntary label.

Water conservation also reduces energy, because heating, pumping and treating water all use it; in buildings with large hot water loads, efficient showerheads cut gas or electricity use as much as water.

What shortens savings:

• Silent leaks in cisterns and pipes.
• Timed urinal flushing running day and night.
• Tampering with flow restrictors by dissatisfied users.
• Unread meters, so waste goes unnoticed.

Water savings decay quickly without maintenance: a cistern valve that starts to pass, a urinal sensor that fails into continuous flushing, or a restrictor removed by a tenant can undo years of savings within weeks, and nothing visible signals it except the meter.

Leaks

Leaking cisterns, dripping taps and hidden pipe leaks waste large volumes silently. In many buildings leaks are a significant share of total use, and night flow on the main meter is the simplest test.

Urinal flushing

Older urinals on timed cisterns flush around the clock whether used or not; replacing them with sensor or waterless systems is one of the largest savings in commercial buildings.

Cooling tower water

Cooling towers lose water by evaporation and bleed; poor water treatment forces excessive bleed. Bleed control tied to conductivity and good treatment raises cycles of concentration and cuts water use.

Low flows in old drains

Very low-flush toilets on long, shallow-graded or old drains can leave solids behind, causing blockages; water efficiency must be matched to the drainage.

User dissatisfaction

Showers with poor spray and taps with weak flow lead users to remove restrictors or complain until fixtures are replaced.

Alternative water system failures

Rainwater and recycled systems that fail revert to mains top-up, so the saving disappears without anyone noticing.

Irrigation waste

Irrigation running on fixed timers in rain, broken sprinklers and leaking drip lines waste water outdoors, often the largest use on landscaped residential sites in summer.

Kitchen and process use

Commercial kitchens, laundries and process equipment such as single-pass cooling of refrigeration and ice machines can use large volumes; single-pass cooling in particular wastes water continuously and is prohibited in some places.

On site and in data

• Night flow on the main meter when the building is empty.
• Cisterns running or trickling into pans.
• Urinals flushing in empty toilets.
• Cooling tower overflow or constant bleed.
• Irrigation running in rain.

In the records

• Water bills and meter data.
• NABERS Water or similar ratings.
• Fixture schedules.
• Cooling tower water treatment reports.

• Wet ground, lush patches or water running in gutters on dry days, which suggest buried leaks.
• Equipment discharging cooling water continuously to drain.
• Rainwater tanks overflowing while the building draws mains water, showing the harvesting system is not connected or working.
• Showerheads and taps with restrictors removed.

Comparing water use per occupant or per square metre with benchmarks shows whether a building is unusually wasteful before any detailed investigation.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

Water findings are rarely urgent for safety, but a large hidden leak can damage structure and finishes, which raises it to a failure grade.

A hydraulic engineer or water auditor leads, with the cooling tower water treatment contractor and landscape contractor where relevant.

• Water audit: consumption broken down by end use (amenities, cooling towers, irrigation, kitchens, process) from bills, sub-meters and fixture counts.
• Night flow test: read the main meter over a period when the building is empty to quantify leaks and continuous flows.
• Fixture survey: flow rates of taps and showers, flush volumes, urinal controls, and condition of cistern valves and seals.
• Cooling tower review: bleed control, cycles of concentration, overflow and drift.
• Irrigation audit: leaks, overspray, controllers and rain sensors.
• Alternative water check: whether rainwater and recycled systems are actually supplying their end uses.
• Drainage check before installing very low-flush fixtures on old drains.

The report should identify the largest uses and losses, quick fixes, fixture upgrades, and a metering and monitoring plan.

• Leak repair of cisterns, taps and pipework, followed by leak alarms on sub-meters.
• Urinal controls: sensor flushing or waterless urinals in place of timed cisterns.
• Efficient fixtures chosen for user satisfaction as well as rating, to avoid tampering.
• Cooling tower bleed control by conductivity with good water treatment.
• Irrigation upgrades: drip irrigation, smart controllers and rain sensors.
• Alternative water restoration: repair harvesting and recycling systems so they supply their end uses.
• Metering with alarms on night flow and unusual consumption.
• Drain upgrades where low-flow fixtures cause blockages.

• Single-pass cooling replacement with air-cooled or closed-loop equipment in kitchens and plant.
• Tenant engagement: share consumption data and include water clauses in leases.

Audits are lump sums. Leak repairs and urinal controls are small itemised costs with quick paybacks. Fixture replacement is per fixture, usually timed with refurbishment. Cooling tower controls and irrigation upgrades are lump sums. Metering is per meter plus a monitoring subscription.

Leak repair is repairs and maintenance; fixture replacement is lifecycle; ratings and restrictions can create deadlines.

Water savings often also cut sewer charges and the energy used to heat and pump water, so paybacks are usually better than the water bill alone suggests.

• Australia. The Water Efficiency Labelling and Standards scheme requires labelling of taps, showers, toilets and urinals; NABERS Water rates offices; water utilities and states impose restrictions in droughts; plumbing codes set minimum efficiency for new fixtures.
• United Kingdom. Approved Document G sets a water efficiency limit for new homes; the Unified Water Label grades fixtures; BREEAM rewards water efficiency in non-domestic buildings; water companies offer audits.
• United States. WaterSense labels efficient fixtures; federal and state standards set maximum flow rates, with stricter limits in states such as California; some cities require water benchmarking alongside energy.

In all three countries, strata and condominium buildings commonly have a single water meter, so individual waste is shared by all owners; sub-metering apartments changes behaviour and is required or encouraged in some places.

• Water bills for at least two years.
• Sub-meter data and night flow readings.
• NABERS Water or similar ratings.
• Fixture schedules with ratings.
• Cooling tower water treatment reports.
• Irrigation controller settings and records.
• Alternative water system maintenance records.

• Records of leaks found and repaired.
• Any water efficiency plan or audit.