How Many HP Pump for a Condo Water Tank (Philippines Sizing Guide)

There is no single HP pump size that fits every condo water tank, because horsepower is an output of three inputs (flow, head, efficiency), not a product category you pick off a shelf. The arithmetic on this page lands in predictable bands.

Treat these as starting brackets, not selections. Two buildings of identical height can differ by a factor of two in required horsepower because one has 32 units and the other 96, or one has a long pipe run with six elbows. Before committing to a motor size, run the numbers below, and before you buy, have the duty point checked against an actual pump curve.

Every HP pump sizing exercise reduces to the same three inputs. Flow is how much water you need to move per hour, written as Q in cubic metres per hour. For transfer duty, divide tank volume by the fill window you will accept: a 20 cubic metre roof tank filled in 4 hours is 5 cubic metres per hour. For a booster duty, flow comes from the fixture demand of the units being served, not from tank size. Head is the total resistance the pump must overcome, written as H in metres: vertical lift to the highest outlet, plus friction losses through pipe and fittings, plus residual pressure at the tap (10 metres of head is roughly 1 bar). Efficiency is the combined pump and motor efficiency: typically 0.40 to 0.50 for small domestic pumps, 0.60 to 0.75 for engineered multistage units. The metric formula is:

kW = (Q x H) / (367 x efficiency)

Convert to horsepower by dividing by 0.746, then round up to the next standard frame. In imperial terms: water HP = (GPM x head in feet) / 3960, divided again by efficiency for brake HP pump output. Get flow and head right and the horsepower falls out of the equation on its own.

Start with the case most people search for: one unit, one small tank, weak shower pressure. Assume you want 30 litres per minute (1.8 cubic metres per hour) so a shower and a kitchen tap can run together. Assume 25 metres of total head: static lift from the tank, friction through 20 mm pipe, and 15 to 20 metres of residual pressure so the shower feels normal. Small domestic pumps are not efficient, so use 0.45. Running the numbers: kW = (1.8 x 25) / (367 x 0.45) = 45 / 165 = 0.27 kW, which is 0.37 HP. Round up to the next standard frame and you have a 0.5 HP pump. This is why 0.5 HP is the honest answer for most single unit condo tanks, and why buying 1 HP because it sounds safer usually just means a noisier pump that short cycles. Before ordering, check your condominium house rules and confirm with the administrator whether a unit-level pump is permitted, drawing from your own tank rather than the building riser. Drawing off a shared riser can pull pressure from neighbours and is commonly restricted.

Building level duties split into two pumps with two different HP pump answers, a distinction generic calculators miss entirely. First, the transfer pump, lifting water from cistern to roof tank. Take a 20 cubic metre roof tank you want filled in 4 hours, giving 5 cubic metres per hour, against a 12 storey lift of about 40 metres static plus 8 metres of friction, so 48 metres total head, at 0.65 efficiency. kW = (5 x 48) / (367 x 0.65) = 240 / 238.6 = 1.01 kW, which is 1.35 HP, so you select a 1.5 HP unit. Second, the pressure booster set, taking water from storage and holding usable pressure at the fixtures. Assume 12 cubic metres per hour of peak simultaneous demand against 55 metres of head, at 0.68 efficiency. kW = (12 x 55) / (367 x 0.68) = 660 / 249.6 = 2.64 kW, which is 3.55 HP, so you select a 4 HP (3 kW) unit. The booster is nearly three times the horsepower of the transfer pump, because it serves peak instantaneous demand rather than a slow scheduled fill. Sizing both from one number is the single most common specification error we see. Our booster pump sizing guide for commercial buildings works through the same math at a whole-building scale.

The instinct on a condo retrofit is to add horsepower as insurance, but it rarely works that way. A pump produces its rated efficiency only near its best efficiency point, so an oversized motor pushed to the far left of its curve runs hot, wastes energy, and shortens seal and bearing life. It also short cycles: the pump reaches cut-out pressure quickly, stops, restarts moments later, and every start is a thermal event the motor absorbs. In a residential condominium that noise transmits through the structure to units nearest the pump room. The correct answer to variable demand is configuration, not raw horsepower. A variable frequency drive lets one pump follow demand instead of hammering on and off, why our control panels are built around Inovance drives through Chutian. A duplex arrangement puts two smaller pumps in lead and lag alternation, so one pump handles normal demand while the second covers peaks and provides redundancy. A correctly charged hydropneumatic pressure tank absorbs small draws so the pump does not start for a hand wash. Together these usually mean less horsepower, not more. For a failing unit already in place, our condominium booster pump replacement covers the Manila swap-out process.

JOHOB Hardware Trading is a Philippines based industrial equipment supplier sourcing from Philippine and Chinese factories, delivering with local warranty and after sales support. For condominium water tank duties we supply established pump brands including Grundfos, DAB and Speroni, alongside CDL Chinese engineered pumps where the spec calls for a more competitive landed cost. Control side, we supply VFD duplex panels, star delta, SDE and MCC panels, built by Chutian around Inovance drives, CE marked. We also supply hydropneumatic pressure tanks, flexible hoses, and valves so the pump room is delivered as a complete package. Water storage is supplied under our sister brand TankSmith, covering FRP modular water tanks, GRP, hot dip galvanised and stainless steel modular tanks, with WRAS certified panels and ISO 9001 manufacturer quality systems. We deliver nationwide across the Philippines, covering NCR, Luzon, Visayas, Mindanao, and the PEZA, SBMA and Clark economic zones. Pricing is quote based rather than published, because horsepower and configuration depend entirely on your building's flow and head.

To return a buildable HP recommendation, send:

• Building height in storeys and vertical distance to the highest fixture
• Number of units, fixture count, or the riser diagram
• Existing tank volumes and fill window you will accept
• Your existing pump nameplate if this is a replacement
• Available electrical supply at the pump room (single phase or three phase, and voltage)
• Delivery address and PEZA or SBMA zone status

Pricing is quote based, 12 percent VAT applies to VAT registered buyers, and zero VAT applies to PEZA and SBMA locators and exporters. Lead times run 21 to 35 days ex stock and 45 to 90 days made to order, so specify a replacement before the current pump stops. We respond within 1 business day.

Reviewed: August 2026