A rainwater tank is a quiet machine. Once every few years it asks for a scrub — and every season, its filters ask for five minutes of attention.

What settles at the bottom

Sediment arrives as a fine slurry and behaves like wet soot. In a 5,000 litre slimline connected to a tiled roof, we typically find between 20 mm and 60 mm of sludge after five years without service. It rarely causes a dramatic failure. Instead you notice the small symptoms: the garden tap runs cloudy for a moment after heavy rain, the pump cycles more often, the water smells faintly earthy in late February, or the cartridge filter you replaced in spring is already brown.

The other half of the problem is organic. Leaf litter that slips past a damaged screen breaks down and feeds a biofilm on the tank walls, particularly in the warm 300 mm just below the waterline. Mosquito larvae need only a finger-width gap in an inlet screen to get in. None of it is dangerous to a fence or a vegetable patch, but it is exactly the material that shortens the life of a $900 pressure pump.

The clean itself, step by step

We arrive with a low-volume sludge vacuum, a tank-wall brush on a telescopic pole, spare screens and gaskets, and a 200 litre holding drum. Nobody needs to climb inside a domestic tank — confined-space entry is the wrong tool for a home job and we do not offer it.

First the roof catchment and gutter outlets get a look, because a clean tank fed by a blocked gutter is a waste of your money. Then we isolate the pump, draw the sediment layer off the base with the vacuum, and brush the walls and roof interior from the inspection hatch outward. Where the tank is nearly empty we finish with a pressure rinse and evacuate the rinse water. Where it is three-quarters full — common after a wet Melbourne winter — we clean without dumping your stored water, and tell you honestly how much of the base we could reach.

Everything we remove leaves with us. Sludge is decanted, dewatered and disposed of through a licensed waste stream; we never tip it down your stormwater drain or across the neighbour's nature strip.

Filters, diverters and screens

The cleaning is the visible half of the work. The lasting half is the hardware. A first-flush diverter that no longer drains between showers becomes a stagnant pipe. A leaf screen sagging away from the inlet collar lets in everything it was installed to stop. A 20 micron cartridge filter left in place for two summers restricts flow badly enough that people replace a perfectly healthy pump.

So every visit includes a hardware pass: we clear and reset the diverter, replace perished inlet and overflow screens, clean the pump strainer basket, flush and re-seat cartridge housings, and fit new cartridges if you want them supplied. You get the old parts back if you ask, and a written note of what was replaced. Details of each item are set out on the services page.

What it costs and how long it takes

A standard clean of a single residential tank takes ninety minutes to three hours, depending on access and how much sediment we lift. Quotes are fixed before we start, given over the phone from a few simple questions, and confirmed in writing.

Slimline tank to 5,000 L — full clean

from $330

Round poly or steel tank, 5,000–10,000 L

from $390

Two tanks on one property, same visit

from $560

Filter & diverter service added to a clean

from $95

Filter service only, no tank clean

from $150

Prices include GST, travel inside 35 km of the CBD, waste disposal and all screens up to 300 mm. Underground and in-slab tanks are quoted on inspection.

Where we work

We cover metropolitan Melbourne: the inner north through Brunswick, Coburg, Preston and Northcote; the inner west through Footscray, Yarraville and Williamstown; the east to Hawthorn, Box Hill and Ringwood; the south-east to Bentleigh, Mentone and Frankston; and the west out to Werribee and Point Cook. Two weekdays each month are set aside for Mornington Peninsula and Macedon Ranges properties, where tanks are larger and usually overdue.