Flooded pool pump rooms in Phuket: causes, damage and protection options

Why underground pump rooms flood

A pump room below ground sits lower than the ground around it. In heavy monsoon rain, water can reach it from several directions at once.

A room that stays dry for most of the year can still flood in a single storm.

The monsoon also brings power cuts. If the drainage depends on mains power and the power fails, the room can fill even where a sump pump has been installed.

• Surface runoff from the garden, terrace or driveway flowing down the stairs or through the hatch
• Groundwater pressing in through the walls and floor as the water table rises
• Drains and soakaways that cannot cope with a sudden downpour
• An overflow or balance tank that fills faster than the system can handle and spills into the plant area
• A sump pump that fails, or loses power during the storm, just when it is needed

What flooding does to the equipment

Pool equipment is built to carry pool water inside its pipes and housings, not to sit in muddy floodwater.

Do not go into a flooded pump room while the power is on: switchboards, sockets and cables in the pit may be live. The supply is isolated and the equipment checked by a licensed electrician before anything is switched back on; the electrician also checks the earthing and earth-leakage protection of the pool circuits. Our inspection after a flood looks at both the pool and the plant, so you can decide with your electrician what can be saved and what needs replacing.

Replacement is often a good moment to rethink the whole system. Old filters, redundant pipes and equipment nobody uses can be removed, so the rebuilt room is simpler to run and easier to protect.

• Pump motors can be ruined when water reaches the windings and bearings.
• Pump strainers, open tanks and valves can fill with silt and debris, and valves can seize.
• Switchboards, controllers and timers can corrode, and the damp keeps attacking them long after the water has gone.
• Water treatment units, lighting transformers and heat pumps can be damaged in the same way.

Option: move the equipment above flood level

Where space allows, the whole pump room can be moved out of the pit to ground level, or even to an upper floor. The pumps, filters and switchboards then sit above the flood level, out of the water's path altogether.

Often the new room can be built while the old one keeps running, so the pool can stay in use for much of the work; the inspection confirms this for each site. The design covers new pipe routes, noise near bedrooms and access for servicing. The electrical supply to the new room is installed by a licensed electrician. We also take the chance to simplify the layout, replace failing equipment and remove redundant lines.

Moving the room works well where there is a spare corner of the garden, a garage, a utility area, an upper floor or a roof terrace close enough to the pool. The pumps and pipe routes are chosen to suit the new position. A room above the pool's water level needs hydraulics designed for the height — pump type, pipe sizes, non-return valves — and a floor drain in the new room so that a leak upstairs does no harm to the house; this is worked out for each site with your engineer.

Option: protect the pump room where it is

Moving the room is not always practical. When the pump room has to stay below ground, several measures reduce the damage a flood can do.

These measures work together, and each is decided per site. Waterproofing reduces seepage through the walls and floor, but it does not stop water pouring down the stairs. Drainage is there for the water that still gets in. Back-up pumps on separate power, and low-voltage battery pumps, mean the drainage does not depend on a single pump or the 220 V supply. All electrical work involved is carried out by a licensed electrician.

Keeping surface water out in the first place — a raised kerb around the stairs or hatch and garden drainage that leads runoff away from the room — is looked at together with the site levels during the inspection.

Battery pumps have limited capacity and run time: they are a last line of defence for overflow tanks and slow seepage, not a substitute for the main drainage pumps, and their batteries are checked during servicing.

• Raising pumps onto plinths above floor level, so a shallow flood is less likely to reach the motors
• Moving switchboards out of the pit to a higher, weatherproof position
• Two or three back-up drainage pumps set at different levels, on separate power supplies
• Low-voltage battery pumps that keep working if the 220 V supply fails
• Level switches that cut the power to the pool equipment if water rises, wired by a licensed electrician
• Emergency drainage for overflow or balance tanks that fill up in storms, including tanks built without an emergency overflow
• Ventilation and air conditioning to control humidity in the room
• Waterproofing walls and floors from the inside, where groundwater seeps in

When garden runoff floods the pool itself

At some villas the problem goes beyond the pump room. Runoff from the garden or the slope flows straight into the pool, bringing mud and debris and flooding the overflow and balance tank.

As part of a remodel, we can raise the pool's perimeter wall and coping above the flood level seen at the site, and adjust the drains and overflow. This work needs the pool drained. It can be combined with lifting the pumps and rebuilding the circulation, so that both are done during the same shutdown.

Garden drainage that carries water away from the pool and pump room also helps. We look at the levels around the pool as part of the inspection.

Who decides what

Flood protection involves several people's responsibilities, so it helps to be clear from the start.

An on-site inspection decides whether the pool stays filled or must be drained. The programme is agreed for each project.

• The owner decides the scope and priorities: whether to move the pump room, protect it where it is, or do both.
• The villa manager or hotel engineer knows the site and how the room has flooded in the past, and when a shutdown can fit around guests.
• Electrical connections for the pool equipment, and any new supply or change to the building's electrical system, are carried out by a licensed electrician and coordinated with your building engineer.
• We inspect the plant, explain what can stay and what should change, and agree the setup with you.
• Engineering decisions are taken with you and your engineer — or, if you do not have one, with our partner engineer.

What to send us for a first discussion

Send us these details so we can review your setup before visiting.

• Photos or a short video of the pump room, switchboard, pipes and pool
• The property location and the approximate pool size
• What you see: how high the water rose, where it came in and what stopped working
• What you want changed, such as moving the pump room, protecting it where it is, or both