An infinity pool plumbing system connects the basin, the overflow edge, the balance tank and the filtration equipment into a coherent hydraulic whole. Each element influences the others: pipe routing, flow direction, pressure losses and water levels must be considered together from the outset.
Unlike a conventional skimmer pool, where small inconsistencies in the plumbing can be absorbed by the system, an infinity pool is less forgiving. Any imbalance in the circuit affects water behaviour at the overflow edge – and therefore the visual result.
This is why infinity pool plumbing is a design discipline, not an installation afterthought.
Plumbing an infinity pool: a system, not just pipes
A conventional pool plumbing system has one primary function: circulate water through the filter and return it to the basin. The circuit is straightforward – skimmers out, filter, pump, inlets back.
An infinity pool operates differently. Water leaves the basin continuously over the overflow edge, collects in the balance tank, passes through the filtration system and returns to the pool through floor-mounted inlets. The circuit is longer, more complex, and subject to continuous variation in flow and pressure.
Every component in this system is interdependent. The pump must be sized against the full circuit – not just the filter. The balance tank must absorb fluctuations in water volume without destabilising the overflow edge. The return inlets must distribute flow evenly across the basin floor.
Designing this system requires understanding how each element affects the others before any pipe is laid.
The external plumbing circuit and why layout matters
The plant room is only one part of the plumbing system. What happens outside – between the pool basin, the overflow edge and the technical room – is equally decisive.
In an infinity pool, water collected at the overflow edge is directed through dedicated pipes toward the balance tank. From there, the pump draws it into the filtration circuit and returns it to the pool through floor-mounted inlets.
The hydraulic layout – the functional design of the circuit before any pipe is sized or drawn – defines how this system will behave. It establishes the sequence of connections, the position of check valves and isolation valves, and the flow logic across each branch. Pipe runs should be as direct as possible, diameters consistent with calculated flow rates, and valve positions correct from the outset – particularly where the balance tank feeds the pump suction line.
The margin for error is smaller than in a conventional pool. A pressure drop in one branch, a valve positioned incorrectly, or a pipe diameter undersized by one step – any of these will show at the overflow edge. The water level shifts, the sheet of water becomes uneven, and the mirror effect is lost.
A clear hydraulic layout eliminates these risks before construction begins and gives the owner a reference document for future maintenance.
For a complete overview of the plant room layout and equipment selection, see our guide on pool pump room design.
From layout to diagram
The hydraulic layout defines the logic of the system. The plumbing diagram – also called a hydraulic plan – translates it into a precise technical document – with pipe diameters, distances, valve positions and equipment references – that allows the installer to work on site without ambiguity.
In an infinity pool, where check valves, safety devices and overflow circuits must be positioned with precision, a diagram removes the risk of interpretation errors. It is particularly valuable when working with contractors who are not specialised in overflow pool construction.
For a complete explanation of what a pool plumbing diagram contains and how to read it, see our guide on swimming pool plumbing diagrams.
Pump and filter sizing for an infinity pool
Sizing the pump and filter for an infinity pool requires more parameters than for a conventional pool. The full circuit must be taken into account, not just the basin volume.
The key parameters are:
- The total water volume of the pool
- The length of the overflow edge
- The type of overflow – infinity edge, zero-edge, deck-level or knife-edge – each generating a different flow load
- The height difference between the balance tank and the pool
- The intended use, private or commercial, which determines the required turnover rate
These parameters determine the pump flow rate and, from there, the filter size. They also define the balance tank volume: the tank must absorb the water displaced by bathers, thermal expansion, and the continuous overflow without destabilising the water level at the edge.
Oversizing the filter is a common mistake: a filter too large for the pump flow rate operates below its optimal velocity, reducing filtration efficiency.
For overflow pools, a dedicated circulation pump for the overflow circuit is sometimes specified separately from the filtration pump, depending on overflow length and hydraulic resistance.
Morana’s advice
The plumbing is calculated, not estimated.
Overflow type, pool volume, pump flow, tank, then the pipe runs. In that order. The other way round shows at the edge.
Frequently asked questions: infinity pool plumbing
What is an infinity pool plumbing layout?
It is the circuit before any pipe is sized. It sets the order of the connections, the position of the valves and the flow on each branch. The plumbing drawing is produced from that layout.
How does infinity pool plumbing differ from a normal pool?
In a normal pool, the pump draws water from the basin, through the skimmers and the main drain. In an overflow pool, infinity or otherwise, the water leaves the basin over the edge. The pump draws from the balancing tank, not from the basin.
How is the balancing tank volume calculated?
From the pump flow. The flow comes from the pool volume, the length of the overflow edge, the type of overflow and the use, private or hotel. The tank is sized for the water that arrives: the water displaced by bathers, and the water added by rain. There is no standard size.It is calculated for each pool.
