Best Valve Setup for Rainwater Tanks in Australia
Three valves do the work on a rainwater tank: a ball valve to isolate, a float valve to refill, a check valve to hold pressure. Specified right, the system runs for years without a callout.
Published May 2026 — 5 min read — For plumbers, tank installers, and rural property owners.
Overview
Engineered for Australian Conditions
Rainwater tanks are widely used across Australia for irrigation, household water supply, and rural properties. The tank stores the water. The valves on the plumbing decide how the system actually performs — how it isolates for maintenance, how it tops up from mains, and how it holds pressure once a pump is in the line.
The question we get from installers and homeowners is the same one every time: what is the best valve setup for a rainwater tank?
The Short Answer
Three Valves, One System
Each valve handles one job. Ball valves for isolation and flow control. Float valves for water-level regulation. Check valves for backflow prevention. Specified in brass, PVC, or 316 stainless to match the environment.
Ball Valve
Manual isolation. On the tank outlet, before the pump, on irrigation lines.
Float Valve
Automatic level control. Cuts mains backup once the tank is full.
Check Valve
One-way flow. Holds pump pressure and stops reverse flow into the tank.
Section 01
Ball Valves for Tank Isolation
Ball valves allow quick control of water flow. Turn the handle a quarter-turn and a rotating ball inside the valve either lets water through or shuts it off completely. No throttling, no guesswork — fully open or fully closed.
On a rainwater tank, ball valves are typically installed in three places:
- On the rainwater tank outlet
- Before the pump
- On irrigation supply lines
Installing a ball valve makes it easy to isolate the tank when performing maintenance — replacing a pump, cleaning a filter, or working on downstream plumbing without draining the tank. Full-bore brass lever ball valves are the standard specification for tank work.
Section 02
Float Valves for Automatic Level Control
Float valves regulate the water level inside the tank automatically. As the water rises, the float lifts and shuts off the incoming water supply. When the level drops, the valve opens and refills the tank.
Float valves are commonly used when rainwater tanks connect to mains water backup systems — the float keeps the tank topped up during dry periods without overflowing when it rains. Browse the float valve range for the right body size and inlet thread.
Section 03
Do Rainwater Tanks Need a Check Valve?
Yes — most rainwater tank systems in Australia require a check valve when a pump or pressure system is installed. A check valve allows water to flow in one direction only and prevents reverse flow back into the tank.
Installing a check valve maintains pump pressure between cycles and protects the stored rainwater from contamination by anything sitting downstream of the pump.
Without a Check Valve
Skipping the check valve on a pump line creates predictable problems:
- Loss of pump pressure between draws
- Water returning to the tank and short-cycling the pump
- Reduced system efficiency and shorter pump life
Section 04
Choosing the Right Valve Material
Material selection matters more on tank installs than on indoor plumbing — these valves sit outside, often in direct sun, sometimes near salt air or fertiliser run-off. Three options cover most of what's installed in Australia.
Brass
Best for: General plumbing, residential tank outlets, pump lines.
DR brass · widely specified · long service life.
Shop brass valves →PVC
Best for: Irrigation installs, agricultural lines, low-pressure runs.
Lightweight · chemical-resistant · cost-effective.
Shop PVC valves →316 Stainless Steel
Best for: Coastal sites, salt air, demanding agricultural environments.
316 grade · corrosion-resistant · long warranty.
Shop stainless valves →Valve Warehouse Australia stocks every material above across the common BSP thread sizes for rainwater and irrigation work — residential and agricultural.
From the Workshop
Plumber Tips
Install a ball valve directly on the rainwater tank outlet and a check valve on the pump line. This setup allows easy maintenance on the pump or downstream plumbing without draining the tank, and prevents water pressure from flowing back into the tank when the pump stops.
Spec quality valves, install them in the right order, and the tank system runs for years without a service call.
The best valve setup for a rainwater tank usually includes a ball valve, a float valve, and a check valve. The ball valve isolates the tank. The float valve controls the water level when the tank is connected to a mains backup supply. The check valve prevents water from flowing backwards in pump systems.
This combination allows the system to operate safely while protecting pumps and plumbing equipment downstream.
Brass for most residential and pump line work. PVC for irrigation and agricultural runs where weight and chemical resistance matter. 316 stainless steel for coastal installs or anywhere salt air and corrosion are a long-term concern. Match the material to the environment and the valve will outlast the tank.
In Stock & Ready to Ship
The Valves You Need, In Stock
Ball, float, and check valves across BSP sizes. Dispatched same-day from Victoria if ordered before 2pm AEST.