Commercial irrigation — budget, liability and control

Establish the water budget and how it will be measured

Before design, agree what the site should use and how that will be evidenced — a dedicated irrigation meter, submeters per area, or flow sensors reporting into the control platform. A number nobody can measure is a target nobody can be held to.

Watch for: Landscape water billed on a combined domestic meter. It makes performance invisible, and it can also mean paying sewer charges on water that never entered a drain. Ask the utility whether a separate irrigation meter is available.

Survey, phase and plan around an occupied site

Commercial installations rarely happen on a clear site. Trenching routes, parking closures, working hours, tenant and resident notice, and traffic management all belong in the plan rather than in a change order.

Watch for: A programme with no phasing. On an occupied site the constraint is access, not digging speed, and a contractor who has not planned around that will discover it at your cost.

Design to a stated uniformity and flow standard

The specification should name the design pressure at the head, the target application uniformity, and the flow budget per zone — so that what was delivered can be verified rather than argued about.

Watch for: A bid that quotes head counts and zone counts but no performance criteria. Without them there is nothing to hold the installer to at handover.

Cross-connection protection to the utility's commercial standard

Commercial connections commonly attract stricter backflow requirements than residential ones, and sites with fertiliser or chemical injection are treated as a higher hazard again. Device type, enclosure, testing interval and tester certification are set by the water purveyor.

Watch for: Backflow treated as a line item rather than a compliance obligation with recurring testing. On a commercial account the testing paperwork is an ongoing duty, and it needs a named owner in the maintenance contract.

Central control, flow sensing and alerting

The operational case for a commercial platform is not convenience — it is the flow sensor and master valve combination that detects an abnormal flow and shuts the affected zone down automatically, rather than letting a broken lateral run all weekend.

Watch for: A control platform specified without flow sensors. Remote scheduling is the smaller half of the value; automatic shutdown on a break is what pays for the system.

Hydrozoning to match how the site is actually used

Zones are separated by exposure, plant type and use — high-traffic turf, ornamental beds, screening planting, and any area scheduled for conversion to lower-water landscape. Separating them now is what allows selective reduction under a drought stage later.

Watch for: Amenity turf and low-water planting sharing a valve. Under an allocation you will have no way to cut one without killing the other.

Overspray, drainage and public-safety detail

Heads adjacent to walkways, entrances and roads need arcs and nozzles chosen so water does not land on pavement, both because it is wasted and because wet paving is a slip and, in freezing climates, an ice hazard.

Watch for: Perimeter heads set to full circle for convenience. It is the most common defect on commercial sites and the one most likely to appear in an incident report.

Handover: as-builts, commissioning data and a service contract

You should receive as-built drawings, a zone schedule, commissioning measurements, controller credentials in the organisation's name, and a maintenance agreement that names response times and defines the boundary between warranty and billable work.

Watch for: Control platform accounts registered to the contractor. On a commercial site this becomes a genuine handover problem at the next tender, and it should be a condition of final payment.