How is irrigation installed on a sports field or public open space?

An irrigation system is the difference between a sports field that recovers between seasons and one that is worn through by midwinter.

It is also a system that fails quietly. A field with an irrigation system that has drifted out of coverage looks like a field with a turf problem.

The water source decides the design

Three sources, and the design follows whichever is available.

**Potable mains,** which is reliable and metered, and on a large field the flow available from a connection is frequently the constraint on how many heads can run at once.

**Harvested rainwater or stormwater,** which requires storage, a pump set and filtration, and which suits a site with roof or hardstand catchment. The storage side sits with [rainwater tanks and reuse on public sites](/answers/rainwater-tanks-and-reuse-on-public-sites).

**Recycled or bore water,** where available, with its own approval requirements and its own water quality considerations for the turf and for public contact.

Each has a different pressure and flow profile, and the head selection, zoning and run times all follow from it. Which is why the source is confirmed by test rather than assumed from a plan.

Coverage and zoning

The objective is even application across the playing surface, because uneven irrigation produces uneven wear and the dry patches are where the surface fails first.

Heads are positioned on a spacing that gives overlapping coverage, since the application rate at the edge of a head's throw is much lower than near it. The spacing depends on the head, the nozzle and the operating pressure, and running a system at a pressure other than its design pressure changes the coverage regardless of how well it was laid out.

Zoning divides the field into groups that can run within the available flow. More zones means a longer total watering window, which matters on a field with early morning use.

Heads on a playing surface are retractable and installed flush, with the body set so the head sits level with the finished surface after the turf establishes. A head standing proud is a trip hazard on a sports field, which makes the installation level a safety item rather than a finish one.

Coordinating with the surface

The irrigation goes in before the turf and after the drainage and the profile, which puts it in a fixed position in the sequence.

Trenching through a prepared profile after it is graded undoes the grading, and installing after turf means cutting it. Which means the irrigation design has to be settled before the field construction begins, alongside the drainage, and that sequence sits with [artificial turf sports field installation](/answers/how-is-an-artificial-turf-sports-field-installed) for synthetic surfaces and with the natural turf works in [turf establishment and landscape maintenance periods](/answers/turf-establishment-and-landscape-maintenance-periods).

Floodlight footings, fence lines, goal post sockets and cricket pitch infrastructure all occupy the same ground, so they are coordinated rather than discovered. The lighting side is covered in [sports field floodlighting](/answers/sports-field-floodlighting).

Backflow prevention and compliance

An irrigation system connected to a potable supply requires backflow prevention appropriate to the hazard, installed, tested and registered.

On a site using recycled or harvested water there is an additional requirement to separate and identify the non-potable system so it cannot be cross-connected, with the pipework, outlets and signage marked accordingly.

Both are compliance items with certification, and both are checked at commissioning rather than assumed.

Working on a field that is used

A field being irrigated is usually a field in use, which means the work is programmed into an off-season or a defined closure period.

Trenching across a field leaves the surface unusable until it recovers, so the extent of open trench at any time is managed and the reinstatement follows immediately behind. Where the field has to remain partly available, the work is staged across the playing area rather than carried out in one pass, which is the same approach as [sports courts and keeping a park open](/answers/sports-courts-park-open-conditions).

Commissioning and handover

Each zone is run and the coverage measured rather than observed, because a system that looks like it is watering can be applying half the intended depth at the overlap points.

The handover includes the as-installed layout showing every head, valve and mainline route, the controller programming, the seasonal schedules, the backflow certification, and the maintenance requirements: head cleaning, nozzle replacement, filter servicing and the annual pressure check.

The as-installed layout is the item the asset owner needs most, because without it the first repair starts with somebody digging to find a pipe.