Home Reverse Osmosis Water Filtration Systems

The sediment filter is the entry point of any reverse osmosis system and one of the most important components for protecting everything downstream. As water enters from your cold-water supply line, it first passes through this filter, which physically traps visible and microscopic particles suspended in the water.

On Vancouver Island — particularly for homes served by older municipal infrastructure or private wells — sediment can be a significant concern. The sediment filter captures:

• Sand and grit — common in well water and during pipe disturbances
• Rust particles — shed from aging iron or steel supply pipes
• Silt and dirt — especially after heavy rainfall or seasonal water table shifts
• Fine debris — any particulate matter that would otherwise clog or damage downstream components

Without this stage, sediment would accumulate on the activated carbon filter and RO membrane, dramatically shortening their service life and reducing filtration efficiency. The sediment filter is the system's sacrificial protector — inexpensive to replace and invaluable in function.

Once the sediment filter has removed physical particles, water flows into the activated carbon filter. This stage uses a highly porous carbon medium — typically derived from coconut shell or coal — that adsorbs chemical contaminants as water passes through its vast internal surface area.

Activated carbon is particularly effective at reducing:

• Chlorine and chloramines — disinfectants added by municipal water treatment that leave unpleasant tastes and odours
• Volatile organic compounds (VOCs) — including pesticides, herbicides, and industrial solvents
• Unpleasant tastes and odours — including the "swimming pool" smell common in city water
• Some heavy metals and disinfection by-products — formed when chlorine reacts with organic matter in the source water

This stage is critically important for protecting the RO membrane in Stage 3. Chlorine is highly oxidizing and can degrade the membrane material rapidly if not removed first. Consider the carbon filter the membrane's bodyguard — it takes the chemical hit so that the membrane can focus on dissolved solids.

The reverse osmosis membrane is the most sophisticated and consequential component in the entire filtration system. It is a semi-permeable membrane with pores so fine — approximately 0.0001 microns — that water molecules pass through while dissolved contaminants are physically blocked and flushed away to the drain line.

The RO membrane is capable of removing an impressive range of dissolved contaminants that no other filtration stage can address:

• Lead and heavy metals — including arsenic, mercury, barium, and cadmium
• Fluoride — one of the most commonly asked-about contaminants; RO is one of the few methods proven to reduce it effectively
• Nitrates and nitrites — a concern for homes near agricultural land or with older septic systems
• Sodium — relevant for households on softened water
• Total dissolved solids (TDS) — the broad measure of all dissolved matter in your water supply
• Pharmaceuticals and emerging contaminants — many are reduced by high-quality RO membranes

During the filtration process, water is split into two streams: purified permeate water, which passes through the membrane to the storage tank, and concentrate (reject water), which carries the trapped contaminants down the drain. This is a normal and necessary part of the RO process.