If you work with reticulated water systems, you've almost certainly come across the distinctive lilac colour that marks reclaimed and recycled supply. Choosing the right recycled water pipe is not just a matter of preference — the colour coding is a recognised safety convention designed to keep non-potable water clearly separated from drinking water. This guide explains what lilac identification means, where purple pipe and fittings are typically required, and how sullage systems differ from pressurised recycled water lines.
Why recycled water pipe is coloured lilac
Across Australia and New Zealand, lilac (often described as purple) is the universally understood colour for non-potable, reclaimed and recycled water. The principle is simple: anyone who later digs up, repairs or extends a line should be able to identify at a glance that the water inside is not safe to drink. This visual cue reduces the risk of a cross-connection — where a non-potable line is accidentally joined to a potable supply — which is one of the most serious hazards in water reticulation.
The lilac convention usually extends beyond the pipe itself. Identification can include the pipe colour, a coloured stripe, printed text along the wall such as "RECYCLED WATER — DO NOT DRINK", and matching lilac valve covers, marker tape and fittings. The goal is consistent, redundant signalling so the message survives even if part of the system is later disturbed or partially buried.
What counts as non-potable water
Non-potable water covers any supply not intended for drinking. In practice that often includes treated effluent reused for irrigation, recycled water schemes feeding garden taps and toilet cisterns in dual-reticulation developments, greywater, and reclaimed stormwater. Because these waters look identical to drinking water, the lilac colour and labelling do the work that clarity alone cannot.
Where lilac recycled water pipe is required
Requirements for colour identification are set by the relevant Australian and New Zealand Standards, plumbing codes, and the rules of the local water authority or regulator overseeing the scheme. Because these vary by state, territory and individual scheme, you should always confirm the specific obligations that apply to your project before you order or install material. As a general guide, lilac identification is commonly called for in:
- Dual-reticulation residential developments, where homes receive both potable and recycled supply through separate networks.
- Commercial and municipal irrigation of parks, sporting fields, golf courses and median strips using recycled or reclaimed water.
- Industrial reuse applications such as washdown, cooling and process water drawn from non-potable sources.
- Agricultural and horticultural schemes distributing treated effluent or recycled supply for crop irrigation.
In all of these settings, the underlying intent is the same: make the non-potable network unmistakable and keep it physically and visually separate from any drinking water line.
Sullage versus pressure systems
Not all recycled and reclaimed water moves through a pipe the same way, and the distinction matters when you're selecting product. Broadly, you'll encounter two categories.
Sullage and gravity systems
Sullage generally refers to wastewater from domestic activities — sinks, baths, laundries — that is collected and conveyed for treatment or reuse. These flows are typically low-pressure or gravity-fed, moving downhill through the line rather than being forced along under significant pressure. Because the hydraulic demands are lower, the priority is reliable conveyance, durability against the material being carried, and clear identification where the application calls for it.
Pressurised recycled water systems
Pressurised recycled water lines, by contrast, are pumped and operate under sustained internal pressure — for example, the supply mains in a dual-reticulation estate or a pressurised irrigation network. Here, the pressure rating of the pipe is critical. Material selected for a pressure application must be matched to the working pressure of the system, and the lilac identification needs to carry through to the pressure-rated pipe, fittings and valves alike. Using a conveyance-grade product on a pressurised line is a serious mismatch, so it's worth confirming the duty of each section before specifying.
The practical takeaway: always be clear about whether a given run is sullage/gravity or pressurised, because that single distinction drives the product class you need just as much as the colour coding does.
Specifying recycled water pipe with confidence
When you're putting a system together, a few habits make compliance straightforward. Confirm the requirements of your local water authority and the relevant standards first. Match the product class to the duty — gravity versus pressure — and keep the lilac identification consistent across pipe, fittings, valves and marker tape. Maintain clear physical separation from any potable line, and document the system so future maintenance crews inherit the same clarity you built in.
As an Australian made and owned manufacturer, RX Rims produces a Lilac reclaimed and recycled water range alongside our broader poly pipe, PVC hose and fittings lines, manufactured to relevant Australian and New Zealand Standards. You can browse our product range to see what's available, and if your project has a specific duty or layout, our team can help you specify correctly.
Need help matching the right lilac product to your sullage or pressure application? Request a quote or contact us and we'll point you in the right direction.