How to Get the Cleanest Water From Your Rainwater Tank

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Collecting rainwater is a smart and sustainable way to manage your household water use, but ensuring that water stays clean from the roof to the tap requires the right setup.

This guide outlines two essential stages and the accessories that help ensure you’re collecting and using the cleanest water possible, before it even gets to your filter.

Stage 1: Clean the Water Before It Enters the Tank

Stopping debris at the source significantly improves the quality of water entering your tank. Two critical accessories can help achieve this:

Leaf Eater

The first line of defence, the Leaf Eater is installed on your downpipe system to catch larger debris like leaves and small branches before they reach your tank.

• Purpose: Filters out coarse debris
• Placement: Inline on downpipes
• Maintenance: Check regularly to remove any leaf build-up from the screen

First Flush Diverter

Even clean-looking roofs can accumulate dust, dirt, and other fine pollutants between rains. The First Flush Diverter captures and discards the first portion of runoff, preventing contaminants from entering your tank.

• Purpose: Removes fine sediment and dust from roof runoff
• Options:
  • 90mm Kit: Suited for 90mm downpipes, this kit does not include a chamber. You'll need to create your own chamber to the desired capacity using 90mm pipe.
  • 120 Litre Kit: Includes a 300mm diameter x 1.2m chamber and accommodates up to 100mm downpipe.
• Maintenance: Must be emptied manually after each rain event

Using both of these accessories together helps ensure that the water entering your tank is as clean as possible from the outset.

Stage 2: Draw the Cleanest Water From Your Tank

While debris that enters the tank will settle at the bottom, the cleanest water sits near the top — about 100–150mm below the surface. Two key accessories can help you avoid drawing from the bottom where sludge and contaminants settle.

Tank Vac

Instead of letting clean water overflow, the Tank Vac system flushes out dirty water from the base of the tank whenever it overflows. It uses gravity and water pressure to siphon off debris that has collected on the floor of the tank.

• Purpose: Flushes debris from the tank floor during overflow events
• Operation: Automatic; activates when tank overflows
• Maintenance: Low. Simply check that the siphon holes are not blocked and that the system is overflowing correctly when full

Floating Outake

The cleanest water in your tank is just below the surface — and the Floating Outake ensures that’s the water you use. No matter the water level, it floats and draws from that ideal height.

• Purpose: Draws water from the cleanest layer
• Operation: Passive; adjusts with water level
• Maintenance: Low. Occasionally check the mesh intake for blockages

What’s the Best Setup?

While each of these components offers benefits on its own, combining all four — Leaf Eater, First Flush Diverter, Tank Vac, and Floating Outake — delivers the best results for water clarity and tank hygiene.

If you're looking for the most effective and low-maintenance combination, the Tank Vac and Floating Outake together offer the greatest impact. They clean your tank and ensure the cleanest water reaches your home — all with minimal upkeep.

Want Help Choosing the Right Setup?

Our team can guide you on the best system for your home.
Call us on 0800 77 66 29 or email sales@promax.co.nz for personalised advice.