Sediment & Rust Water Filters

Sediment in mains water comes from old pipes, repairs upstream of your meter, and treatment plant turbidity events. Sediment in tank water comes from the catchment — leaves, dust, bird debris, and the slow accumulation of fine silt at the bottom of the tank. Rust comes from iron pipes and is either suspended (visible coloured particles) or dissolved (clear water that stains).

Sediment filtration is the simplest, cheapest filter type. It is also the most important — sediment cartridges protect every downstream stage from premature clogging.

What you need to know:

• Spun polypropylene cartridges — the cheapest, single-use, replaced when the pressure drop is noticeable. Standard for most installs.
• Pleated washable cartridges — last longer, can be hosed off and reused several times. Good for rainwater and bore water properties that load filters fast.
• Carbon block — incidentally a sediment filter as well as a chlorine filter. Rated to about 5 micron.

How to choose

• Town water, occasional discoloured water from upstream repairs? Single-stage 5 micron under-sink filter is enough. Cheap to buy, cheap to replace.
• Rural property on tank or bore water? Whole-house, 2-stage minimum. 20 micron first stage to catch the gross debris, 5 micron polish behind it. Pair with carbon and UV downstream if you drink the water.
• Rust-stained fixtures and clear water? That is dissolved iron, not suspended sediment. You need an iron-removal stage (oxidation followed by filtration). Get a water test to confirm before ordering.

Pressure drop is the giveaway that a sediment cartridge needs replacing — when fully-open taps run noticeably slower than they did a month ago, the cartridge is loaded. Most whole-house housings have a pressure release button so changes are a five-minute job.