4-Stage RO / RODI Filter Replacement Kit – Sediment, Carbon Block & 1L DI Resin Refill

Keep your 4-stage reverse osmosis system producing ultra-pure water with this complete, hassle-free replacement kit from Osmotics. Specially designed for our popular 4-stage domestic RO and RODI units, this kit restores peak performance by refreshing the essential pre-filters and deionisation stage—ensuring crystal-clear, contaminant-free water for drinking, aquariums, window cleaning, or laboratory use.

This convenient bundle saves you time and money compared to buying filters separately, with everything you need in one box. Each component is manufactured to high standards using premium materials for reliable contaminant removal and long service life.

What's Included

• 1 × 5 Micron Sediment Pre-Filter (10" × 2.5") — Traps dirt, sand, rust, silt, and particles larger than 5 microns to protect downstream stages.
• 1 × Carbon Block Pre-Filter (10" × 2.5") — Removes chlorine, chloramine, bad tastes/odours, organic chemicals, and pesticides—safeguarding your RO membrane from chemical damage.
• 1 Litre DI Resin (supplied in a sealed, pharmaceutical-grade container) — High-quality mixed-bed deionisation resin for final polishing, removing remaining dissolved solids and achieving zero TDS ultra-pure water.

Key Benefits

• Restores full system efficiency — Replaces worn filters to maintain high flow rates, optimal rejection rates, and pure water quality.
• Protects your investment — Fresh pre-filters prevent premature RO membrane fouling; fresh DI resin ensures consistently low TDS output.
• Great value & convenience — One-stop kit at a competitive price (£20.40), with fast UK delivery and easy DIY installation—no specialist tools required.
• Ideal for UK water — Perfect for areas with variable tap water (chlorine, sediment, hardness), borehole supplies, or high-purity needs like reef aquariums and spot-free rinsing.

Compatibility

Fits standard 4-stage Osmotics reverse osmosis systems (and most compatible 10" housings). Note: This kit does not include the RO membrane—replace the membrane separately every 2–3 years (or when TDS creep occurs).

Recommended Replacement Schedule (varies by water quality & usage)

• Sediment & Carbon Block filters: Every 6–12 months (or sooner if flow slows or water tastes off).
• DI Resin: Every 6–18 months (monitor output TDS; resin exhausts faster with higher input TDS after the RO stage). Replace when you notice reduced production, higher TDS readings, or discoloured filters.

Specifications

• Filter Size: Standard 2.5" × 10"
• Material: Food-grade polypropylene (sediment), extruded carbon block, premium mixed-bed DI resin
• SKU: OS-4SFRK
• Weight: 1.1 kg

This bestselling kit has earned 100% positive reviews for a reason—it's a simple, effective way to keep your Osmotics system delivering exceptional pure water year after year. In stock now with next-day UK options available.