Where Should a Pool Overflow Go? Rules by Water Utility

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Where should my pool overflow go? To the stormwater system, a tank or a seepage drain, not the sewer: every utility we read that addresses rain keeps it out by default. Unitywater wants a skimmer-box overflow pipe to stormwater, a tank or a seepage drain, and allows sewer only by application through a pipe no wider than 40 mm.

The short answer

Rain in a pool is rainwater. Unitywater, Moreton Bay council and Icon Water keep rain overflow out of the sewer; Sydney Water and Hunter Water bar stormwater from their sewers outright.
Unitywater’s three destinations: a licensed plumber and drainer runs an overflow pipe from the skimmer box to private stormwater drains (then the kerb or an overland flow path), a storage tank for the garden, or a seepage sump or drain the council recommends.
Sewer only by exception: Unitywater needs a written application and then limits the overflow pipe to 40 mm internal diameter with its invert at least 50 mm above top water level.
Moreton Bay council (August 2025): overflow such as rainwater goes to the roof water system; backwash and emptying go to sewer via the overflow relief gully.
Do not use backwash to beat the rain. A Fraser Coast council guideline calls draining a pool through the backwash in heavy rain illegal; Hunter Water bans backwash during rain.

Where a pool’s rain overflow goes, utility by utility: the destination each publishes and whether the sewer is allowed, with the document and date. Read 22 October 2026; the Fraser Coast guideline from a web.archive.org copy of March 2023
Utility or council	Where rain overflow goes	Sewer allowed?	Document
Unitywater (Moreton Bay, Sunshine Coast, Noosa)	A skimmer-box overflow pipe, installed by a licensed plumber and drainer, to private stormwater drains discharging to an overland flow path or the kerb and channel; or a storage tank used on the garden; or a seepage sump or drain as the council recommends	Only by written application, with a builder’s or plumber’s statement of why no alternative works; pipe internal diameter no more than 40 mm, invert at least 50 mm above top water level	OP8130 rev 10, amended 21 April 2026
Moreton Bay council	“Drainage of the overflow e.g. rainwater, is to discharge to the roof water system”	Backwash, and emptying, go to sewer via the overflow relief gully	Fact sheet, August 2025
Icon Water (Canberra)	Not addressed beyond the sewer	No: pool overflow from rainwater entry or overfilling, “Rainwater is not permitted to enter the sewer”	Acceptance guideline 7, August 2016
Hunter Water (Newcastle, Lake Macquarie)	Not addressed for pools	No: “You must NOT discharge stormwater or groundwater” to its sewer; backwash not during rain	Wastewater connections standard v4, March 2024
Sydney Water	Not addressed for pools	No: “You must not discharge stormwater or roof-water to our wastewater system”	Connection policy v3, 2020
Wide Bay Water (Fraser Coast council)	Not stated; suggests a backwash storage tank for reuse	Using backwash to drain a pool in heavy rain is “illegal”; isolate backwash in heavy rain	Sewer overflow guideline (archive copy, March 2023)
Water Corporation (Perth and WA)	Your local government decides	No: domestic pool drainage “not permitted to be discharged to sewer”	Aquatic facilities page, read 22 October 2026

Where should my pool overflow go?

To the stormwater side of your property: the pipes that take roof water, a rainwater tank, or a seepage drain. Unitywater’s policy defines overflow water as “rain or surface water that is captured in the swimming pool” and drained to stop it overflowing, and it will not accept it into the sewer unless satisfied there is no safe and practical alternative, because sewers are not built for rainwater and overflow in wet weather. Moreton Bay council’s fact sheet sends “drainage of the overflow e.g. rainwater” to the roof water system. Icon Water: “Rainwater is not permitted to enter the sewer.”

The rain-in, rain-out rule: water that fell into the pool as rain leaves by the stormwater path; water you filtered and chlorinated leaves by whatever path your utility sets for backwash. In Queensland and Canberra those are different pipes, and sending rain to the sewer gully is the mistake the rules are written against.

The catch is on your side of the boundary: the stormwater pipe on your block must still discharge somewhere lawful, which is why Unitywater says to consult the council, which owns the kerb and overland flow paths.

Pool overflow to stormwater: what the pipe looks like

A fixed pipe from the skimmer box, not a hose. Unitywater’s policy has a licensed plumber and drainer install “an overflow pipe connecting the swimming pool skimmer box” to private stormwater drains that discharge to an overland flow path or the kerb and channel. Because the pipe starts at the skimmer, it only runs once the water rises above the normal level; nothing drains on a dry day.

Where Unitywater does approve a sewer connection, it fixes the geometry: internal diameter no more than 40 mm, invert at the skimmer box at least 50 mm above the pool’s top water level. Those two numbers are the only published overflow pipe dimensions we found for a household pool. Pipework that connects to drains is plumbing work; see whether pool pipework is plumbing work.

Pool overflow to a soakwell or seepage drain

Allowed by Unitywater where the council recommends it. It defines a seepage sump or drain as “a hole (shaft) or trench that is filled with sand and/or gravel to enable water discharged to the shaft or trench to seep into the ground”, and leaves the design to the local government. In Perth, where soakwells are common, Water Corporation refers pool water questions to local government and we have not yet verified a council rule; the WA sewer page explains why the answer there is local.

A storage tank is the third option: Unitywater suggests using the overflow on the garden in dry weather, and Wide Bay Water suggests a backwash tank for the same reason.

Can my pool overflow go into the sewer?

Almost never by default. Sydney Water: “You must not discharge stormwater or roof-water to our wastewater system.” Hunter Water: “You must NOT discharge stormwater or groundwater to Hunter Water’s sewerage system.” Icon Water: rainwater is not permitted. Unitywater: only after a written application with a statement from the builder or a licensed plumber and drainer on why each alternative is not viable, and a drawing.

Water Corporation in WA does not accept domestic pool drainage into the sewer at all. Sydney Water’s pressure-sewer supplement adds one more case: where a council asks a property on a pressure sewer to send pool water to the wastewater system, the flow must be held under 0.5 L/s by a holding tank, an extra pump or a flow-limiting valve.

Why the backwash rule and the overflow rule are different

Because one is wastewater and the other is rain. Unitywater accepts backwash and maintenance water to its sewers at up to 0.5 L/s; Hunter Water accepts residential backwash at up to 1 L/s, but not while it is raining; Moreton Bay sends backwash and emptying to sewer and overflow to roof water. Icon Water allows a domestic pool’s contents to sewer only when pumping to the environment or stormwater is not feasible. The NSW sewer rules are about backwash and draining, not rain.

A Fraser Coast council guideline says it is “illegal and immoral to use backwash systems to drain pools during heavy rain events”, and asks owners to isolate backwash in heavy rain. If the pool is already too full after a storm, how to lower pool water level after rain covers the manual method and each utility’s rate cap.

If you are building: put the overflow in the quote

An overflow is cheapest when it goes in with the pool. Ask each builder where the overflow will discharge, whether it ties into the house stormwater, and who lodges anything the utility or council needs, then compare pool quotes with that line in every quote. Where draining or lowering the pool is the real question, see how to drain a pool and whether you can drain a pool into the street. Builders are listed for Moreton Bay, the Sunshine Coast and Canberra.

Common questions

Where should a pool overflow pipe drain to?

To private stormwater drains, a storage tank or a seepage sump or drain. Unitywater’s pool wastewater policy lists those three and accepts overflow into the sewer only by application.

Can pool overflow go to stormwater?

Yes, where it is rain overflow and your council accepts the discharge point. Moreton Bay council sends overflow such as rainwater to the roof water system.

Can a pool overflow go into a soakwell?

Unitywater allows a seepage sump or drain in line with the local council’s recommendations. In WA, ask your local government; Water Corporation refers pool water questions to it.

Can pool overflow go into the sewer?

Generally no. Sydney Water, Hunter Water and Icon Water bar stormwater or rainwater from the sewer; Unitywater needs a written application and then limits the pipe to 40 mm.

What size should a pool overflow pipe be?

The only published figure we found is Unitywater’s, for overflow to sewer: internal diameter no more than 40 mm, with the invert at least 50 mm above top water level.

Sources

General information only, current at 2026-10-22. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.

Where should a pool overflow go?