Bidadari’s park views are easy to appreciate. What’s less obvious is the underground reservoir with enough drinking water to fill 3 Olympic-sized swimming pools that is hidden beneath all that greenery.
Tucked beneath part of Bidadari Park, the underground reservoir was designed to support around 8,800 households in the estate by providing them with consistent water pressure and a stored drinking water supply.
2 underground tanks hold Bidadari’s hidden water reserve
The pumping station outside (left) and one of the underground water tanks (right).
Image credit: PUB
3 Olympic-sized swimming pools sounds like a lot, until you look at the rest of Singapore’s water network. Tengah’s new service reservoir, completed in June 2026 for about 42,000 future households, holds around 22 pools’ worth, roughly seven times Bidadari’s. And Bedok Reservoir, which stores untreated water for the whole island, holds the equivalent of more than 5,000.
In Bidadari’s case, it only needs to serve about 8,800 households, topping up supply at peak hours, keeping water pressure steady and acting as an emergency backup.
Up to 5 pumps help keep the water flowing during busy hours
The underground pumps (left) and automated control room (right).
Image credit: PUB
Most of Singapore’s service reservoirs sit on high ground, so gravity does the heavy lifting. Water simply flows downhill to the taps. Tengah’s new reservoir works this way, drawing on the highest point in the town.
On the flip side, Bidadari’s reservoir sits low, beneath the park, so it relies on up to 5 pumps, run from a central control room, to push water out to the estate.
How it works is simple: during off-peak hours, the tanks refill with treated water from service reservoirs on higher ground. When usage picks up, the pumps switch on and send that stored water into the pipes.
Building beneath Bidadari Park saved 1,500sqm of land
Because most of the facility is buried, about 1,500 sqm of land was freed up, and the space over the tanks became part of Bidadari Park. That’s roughly 3.5 basketball courts’ worth of green space.
A conventional reservoir of this capacity would have taken up about three times as much space. Here, the only part you can see is the pumping station, about 700 sqm, or roughly the floor area of 8 four-room HDB flats put together.
Bidadari was planned with greenery in mind. About 15% of the estate’s land is set aside for green spaces, and the 13-hectare Bidadari Park, which opened in September 2024, is a big part of that. Laid out as floor space, it would fit roughly 1,200 5-room HDB flats, but it’s all lawns, trees and jogging paths instead.
Alkaff Lake holds back rainwater so nearby drains don’t flood
Alkaff Lake holds stormwater during heavy rain, while the underground reservoir stores drinking water.
Image credit: PUB
If you’ve walked past Alkaff Lake, you might wonder how it fits in. The reservoir underground stores drinking water. The lake deals with rainwater.
When it pours, runoff from about half of Bidadari estate flows into the lake, which sits at the lowest point of the area. From there, outlets let the water out slowly into the drains downstream, so they don’t get flooded all at once. The lake can hold up to 40,000 cubic metres, or about 16 Olympic-sized swimming pools. That’s on top of the 3 pools’ worth of drinking water stored underground.
The lake can hold up to 40,000 cubic metres of water, equivalent to 16 Olympic-sized swimming pools. That’s a separate capacity from the 3 pools’ worth stored underground.
You also might be wondering, why don’t we just build bigger drains? The fact is that you can’t just dig wider drains in an estate that’s already built up. The lake is the workaround, a place for rainwater to sit before it trickles out.
Bidadari’s underground reservoir that houses residents’ tap water
Next time you’re walking through Bidadari Park, spare a thought for what’s underneath. Past the homes, the paths and the lake, there’s a reservoir quietly doing its job below your feet.
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Cover image adapted from: PUB
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