Davey Microlene KAS20J Whole House Water Filter - 2 Stage Rainwater, 20" Jumbo Housings NZ

Davey Microlene KAS20J — Whole House Water Filter for Rainwater and Tank Water

Cleaner, clearer tank water at every tap — with longer cartridge life.

The Davey Microlene KAS20J is a 2-stage whole-house filter kit designed for rainwater and tank water supplies. The first stage removes coarse sediment, dirt, rust, and leaf matter. The second removes fine particles and parasitic cysts — so the water reaching your taps, appliances, and UV system is clear and well prepared.

The kit uses 20" Jumbo housings. Longer than the 10" version, these housings hold more cartridge media — which means higher capacity and longer service life between changes. Well suited to larger homes, high-usage households, or properties where the 10" kit would need servicing too frequently. If your property has very high flow demands, two kits can be installed in parallel.

Connection fittings are not included. The housings use 25mm (1") FBSP connections — standard NZ plumbing size.

Bore water quality varies significantly. We recommend testing your bore water before selecting a filtration system — get in touch and we'll help you choose the right configuration for your supply.

How It Works

Stage 1 — 20 Micron Poly Pleated Cartridge

Removes larger sediment, dirt, rust, and leaf matter from rainwater and tank supplies. Recommended cleaning every 3–6 months and replacing every 12 months.

Stage 2 — 1 Micron Poly Spun Cartridge

Removes fine particle sediment and parasitic cysts. Recommended replacing every 6–12 months.

Key Specs at a Glance

• Housing size: 20" Jumbo (114mm / 4.5" OD cartridges)
• Water source: Rainwater and tank water
• Connections: 25mm (1") FBSP
• Max system pressure: 880 kPa (128 PSI)
• Water temperature: 0–40°C
• Stage 1 cartridge life: Clean every 3–6 months, replace every 12 months
• Stage 2 cartridge life: Replace every 6–12 months
• Housing material: Glass reinforced polypropylene
• Compliance: Tested to AS/NZS 4020 for use in contact with drinking water

What's in the Box

• Twin 20" Jumbo filter housings
• 20 micron poly pleated cartridge (Stage 1 — coarse sediment)
• 1 micron poly spun cartridge (Stage 2 — fine sediment and cysts)
• Housing spanner
• Fixings for bracket

Warranty

• 1 year — housings

Frequently Asked Questions

Is this suitable for rainwater and tank water only?

Yes. The KAS20J is configured for rainwater and tank water supplies — the cartridge combination is designed to handle the variable sediment loads typical of roof-collected water. For mains water, the KAS20JM uses a different cartridge combination better suited to town supply. Get in touch and we'll point you in the right direction.

What's the difference between the KAS10J and KAS20J?

Both use the same cartridge combination for rainwater. The 20" version uses longer cartridges, which increases capacity and extends the time between cartridge changes. If you have a larger household or higher usage, the 20" is the better fit.

Do I need a plumber to install it?

For most customers, yes — a licensed plumber is the safest path and protects your warranty on the plumbing side. The KAS20J uses standard 25mm (1") FBSP connections and wall-mounts with the included fixings. If you're confident with household plumbing, the installation itself is straightforward. If you're not sure, get in touch and we'll help you decide.

What connection fittings will I need?

The housings have 25mm (1") FBSP connections. Connection fittings are not included — your plumber can supply these from any plumbing merchant.

How often do I replace the cartridges?

Stage 1 — clean every 3–6 months and replace every 12 months. Stage 2 — replace every 6–12 months. Rainwater quality varies with weather and season, so replace sooner if you notice a drop in flow or change in water clarity.

Can I pair this with a UV system?

Yes. This filter kit is well suited as pre-filtration upstream of a UV disinfection system — removing sediment before it reaches the UV chamber helps maintain UV treatment effectiveness. Get in touch and we'll advise on the right UV pairing for your supply.

Do I need bypass valves?

Bypass valves aren't included and we don't stock them, but we strongly recommend your plumber fit them on either side of the system. They let you isolate the unit for servicing without cutting off your water supply. Any licensed plumber or plumbing merchant can supply and fit them.

What if I need even higher flow rates?

Installing two kits in parallel is recommended when higher flow rates are required. Get in touch and we'll advise on the right setup for your property.

What warranty comes with it?

1 year on the housings.