Specialist Hydraulics

Specialist hydraulics covers water systems beyond ordinary supply and drainage: swimming pools and spas with their filtration, heating and chemical dosing plant; rainwater harvesting and recycled or greywater systems that supply toilets, irrigation and cooling; water features and fountains; and irrigation systems. Each brings its own hazards: drowning and suction entrapment, toxic chemicals, cross-connection of non-drinking water into drinking supplies, and Legionella from aerosols.

Recycled and harvested water is carried in separately identified pipes (purple or lilac in Australia and the United States, with marked pipes in Britain) and must never be connected to drinking water outlets. Most cross-connections are created years after construction by plumbers who did not recognise the pipe.

What shortens life:

• Poor water chemistry in pools, which etches finishes, corrodes metalwork and damages plant.
• Corrosive plant rooms where chlorine fumes attack electrical equipment, steel and controls.
• Neglected treatment of recycled and harvested water, which lets systems foul and smell.
• Ground movement and leaking pool shells that undermine surroundings.

Suction entrapment

Pool and spa outlets with single drains, missing or broken covers, or flow rates too high for the cover can trap hair, limbs or bodies against the outlet, causing drownings and serious injuries, particularly to children. Dual drains, compliant covers and safety vacuum release systems prevent it; older pools often lack them.

Chemical hazards

Chlorine and acid stored or dosed together, or mixed by accident during deliveries, release chlorine gas. Plant rooms without ventilation, bunding, separation of chemicals and signage put staff and the public at risk; dosing failures overdose or underdose pools.

Microbial contamination

Pools and spas with poor filtration, disinfection or turnover grow bacteria and parasites; spas are the highest risk because of warm water and aerosols, and are a known source of Legionella.

Cross-connection

Recycled, greywater and rainwater pipes connected to drinking water outlets, or drinking water top-up connections without backflow protection, contaminate the drinking supply. The risk grows with every later alteration.

Pool barrier failures

Pool fences and gates that do not self-close and self-latch, gaps under or through fences, and climbable objects placed nearby defeat the barriers that prevent child drownings.

Pool shell and finish failure

Pool shells crack and leak through ground movement and failed waterproofing; finishes etch, delaminate and loosen tiles; leaks undermine surrounding paving and structures, and on podium pools leak into car parks and plant below.

Water features and aerosols

Fountains and water features recirculate warm water and create aerosols; without treatment and cleaning they grow Legionella and have caused outbreaks.

On site

• Pool outlet covers: present, intact, secured, compliant labels; number of drains.
• Pool fences and gates: self-closing and self-latching, heights, gaps, climbable objects nearby.
• Plant room: chemical storage separation, bunding, ventilation, smell of chlorine, corrosion of equipment.
• Pool surfaces: etching, loose tiles, cracks, water loss.
• Recycled and rainwater pipes and outlets: colour and labelling, signage at taps.
• Water features: cleanliness, slime, foam, treatment equipment.
• Staining or leaks under podium pools.

In the records

• Pool water testing logs.
• Pool barrier compliance certificates.
• Chemical safety data and storage register.
• Recycled water validation and testing.
• Water feature Legionella management.
• Leak and repair history.

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).

A pool and aquatic specialist, hydraulic engineer and, for water quality, a water hygiene specialist.

• Pool safety inspection: outlet covers and their ratings, number and spacing of drains, safety vacuum release systems, signage, depth markings and lifesaving equipment.
• Barrier inspection against the applicable standard: height, gaps, gates, latches, non-climbable zones, and any certificate or registration requirements.
• Plant room inspection: chemical storage and segregation, bunding, ventilation, dosing controls, electrical condition, confined space status.
• Water quality review: testing logs, turnover rates, filtration performance, disinfection levels; laboratory sampling where needed.
• Leak investigation of pool shells and pipework by bucket, dye and pressure tests.
• Cross-connection survey of recycled, greywater and rainwater systems by tracing and dye testing.
• Water feature review under a Legionella risk assessment.

The report should state safety defects and immediate actions, regulatory compliance, water quality management, plant condition and remaining life, and a capital plan.

• Outlet upgrades: compliant anti-entrapment covers, dual drains or safety vacuum release systems, and flow rates within the cover rating.
• Barrier rectification: self-closing and self-latching gates, heights and gaps fixed, climbable objects removed, and certification obtained.
• Plant room upgrades: separated and bunded chemical storage, ventilation, automatic dosing with alarms, signage and emergency procedures.
• Pool refurbishment: shell repairs, new waterproofing, finishes, tiles and coping.
• Filtration and plant replacement sized to the bather load and turnover required.
• Cross-connection removal, with backflow protection on drinking water top-ups and clear labelling.
• Treatment upgrades for recycled water systems, with validation and monitoring.
• Water feature treatment and cleaning regimes, or decommissioning.

Water testing, plant maintenance and barrier inspections recur. Outlet and barrier rectification are lump sums and usually urgent. Plant room upgrades and pool refurbishment are lump sums, with refurbishment closing the pool for weeks. Pool plant replacement is per item. Recycled water plant overhauls are lump sums with membrane and UV lamp replacement on cycles.

Safety and barrier rectification are code compliance; refurbishment and plant replacement are lifecycle; maintenance is repairs and maintenance. In apartment buildings, pools are often one of the largest sinking fund items.

• Australia. Pool barriers follow AS 1926.1 with state registration and certification regimes (for example in New South Wales and Queensland); outlets follow AS 1926.3; public pools are regulated by state health departments; recycled and rainwater systems follow AS/NZS 3500.1 and state health guidelines.
• United Kingdom. HSG179 sets health and safety guidance for swimming pools, and the Pool Water Treatment Advisory Group (PWTAG) sets water treatment practice; rainwater harvesting follows BS EN 16941-1 and BS 8515; the Water Supply (Water Fittings) Regulations govern cross-connections.
• United States. The Virginia Graeme Baker Pool and Spa Safety Act requires anti-entrapment drain covers on public pools and spas; the Model Aquatic Health Code and state health codes govern public pools; ASHRAE 188 covers Legionella risk in features and spas; plumbing codes cover non-potable water systems.

• Pool barrier compliance certificates and registration.
• Pool water testing logs and health department inspection reports.
• Outlet cover specifications and installation dates.
• Chemical storage register and safety data sheets.
• Recycled or rainwater system validation and testing records.
• Water management plan covering spas and features.
• Pool refurbishment and leak history.