Trevoli Big Blue 20 Inch Single Filter Housing - Option 4, Rainwater & Tank Water NZ

Simple, effective sediment removal for rainwater and tank water — in a larger 20 inch jumbo format. This single 20 inch jumbo filter housing comes pre-fitted with a Pentair Dual Gradient 25-1 filter, delivering dual-stage sediment filtration in a single cartridge.

The 20 inch jumbo format provides more filter media than a 10 inch housing — greater sediment holding capacity and longer cartridge life between changes. Suited to medium homes on tank or rainwater supply where a single-housing setup with higher capacity is the priority.

Housing arrives assembled with spanner and standard bracket. Select your bracket or stand option and pressure gauge from the dropdowns.

Key specs at a glance

• Housing size: 20 inch jumbo (single)
• Inlet/outlet: 25mm (1" BSP), brass lined
• Filter: Pentair Dual Gradient 25-1 — 25 to 1 micron dual gradient sediment
• Maximum operating pressure: 125 PSI
• Material: Food-grade, quality brass lined ports
• Pressure relief button: Yes (air bleeder)
• Comes assembled with spanner and bracket
• Warranty: 2 years (housing)

Configure your set

Bracket/stand (select from dropdown):

• Standard powder-coated bracket (included)
• Stainless steel bracket (upgrade)
• Stand (upgrade) — freestanding combined stand and bracket unit

Pressure gauge (select from dropdown):

• No pressure gauge
• Pressure gauge (add-on)

About the Dual Gradient filter

The Pentair Dual Gradient 25-1 is a single cartridge that does the work of two sediment stages. It filters at 25 micron on the outer layer and progressively finer toward the centre, finishing at 1 micron. Coarser particles are caught in the outer layer, finer particles deeper in — this depth-loading design means the cartridge holds more sediment before restricting flow.

The 20 inch version contains more filter media than the 10 inch — greater capacity and longer service life between replacements.

Why choose this system

• Single housing, dual-stage filtration — the Dual Gradient does the work of two cartridges in one
• 20 inch jumbo format — greater sediment holding capacity and longer cartridge life than Option 1
• Compact single-housing setup — one connection, one cartridge
• Suited to tank and rainwater sediment removal — removes silt, sand, rust, and fine particles
• Quality brass lined 1 inch inlet and outlet — durable and corrosion-resistant
• Powder-coated bracket included — optional stainless steel upgrade or freestanding stand
• Optional pressure gauge — monitor filter life without guessing
• 2-year warranty on housing

Technical specifications

What's in the box

• 1x Big Blue 20 inch jumbo filter housing
• 1x Pentair Dual Gradient 25-1 filter (20")
• Housing spanner
• Standard powder-coated bracket (unless upgrade selected)
• Pressure gauge (if selected)
• Stainless steel bracket or stand (if selected)

Frequently asked questions

What is the difference between Option 1 and Option 4?

Both use the same Pentair Dual Gradient 25-1 cartridge and deliver the same dual-stage sediment filtration. The difference is housing size — Option 1 uses a 10 inch jumbo housing and Option 4 uses a 20 inch jumbo housing. The 20 inch format holds more filter media, giving longer cartridge life and better performance at higher flow rates. It's the better choice for medium homes or properties with higher daily water demand.

What is the Dual Gradient 25-1?

It's a Pentair dual gradient sediment cartridge — one filter that transitions from 25 micron on the outside to 1 micron toward the centre. Coarser particles are caught in the outer layer, finer particles deeper in, combining two stages of sediment filtration in a single cartridge.

Is this suitable for mains water?

This system is designed for sediment removal from tank and rainwater supplies. For mains water, the priority is typically chlorine and taste reduction — get in touch and we'll point you to the right option.

When do I replace the filter?

Replace every 6–12 months depending on your water quality and usage. The clearest sign is a drop in water pressure or flow rate. In high-sediment water — common after heavy rain or in summer — you may need to replace more frequently.

What's the difference between the bracket and stand options?

The standard and stainless steel brackets mount the housing to a wall. The stand is a freestanding combined stand and bracket unit — it doesn't require wall mounting, which suits installations where wall mounting isn't practical.

Should I add a pressure gauge?

A pressure gauge lets you monitor the pressure drop across the filter — when pressure drops noticeably it's a reliable sign the cartridge needs replacing. Useful if you want to track filter life without guessing.

Do I need a plumber to install it?

For most customers, yes — a licensed plumber is the safest path. The housing uses standard 25mm BSP fittings and arrives assembled with a housing spanner. If you're confident with household plumbing, the installation is straightforward. Get in touch if you're unsure.

What warranty does it come with?

2 years on the housing. Filter cartridges are consumables and don't carry a standard product warranty.