1.76kg of phosphate betterment, delivered and signed off in the Parrett catchment

Overview

Developers in the River Parrett catchment need to demonstrate nutrient neutrality before permission is granted. When a developer purchases phosphate credits from WCI, that purchase funds the replacement of an ageing private system somewhere in the same catchment. The credits secure the permission; the upgrade gets paid for; the phosphate load comes off the river.

Upgrades are delivered as credits are required when planning permissions are granted for various size developments, so householders who register are joining a queue whose pace is set by development activity in the catchment, not by WCI’s capacity to install. For developers, that is the point worth noting: WCI holds a portfolio of registered properties surveyed and ready to upgrade, so credit supply is not constrained by finding suitable sites.

Senga’s property is one of those upgrades. This is what the transaction looks like at the other end.

The Property

Senga had lived with the same septic tank for decades. It had not failed and she was under no notice to replace it. What she had was an installation date — the early 1950s — and a sensible suspicion about what that meant for a system three-quarters of a century old.

“I didn’t know that I needed to, but I did know that my septic tank was put in in the early 1950s, so it was likely to be in trouble.”

She registered after a neighbour 300 yards up the road, whose system WCI had already replaced, told her to get her name down.

This is the profile that makes the model work. Systems of this age are not on anyone’s enforcement list. They are not discharging visibly. They are simply old, unsealed by modern standards, and contributing phosphate to the catchment every day.

The WCI Installation

WCI surveyed the property, specified a Graf One2Clean sewage treatment plant to replace the existing tank, and installed in June 2026. Access was taken through the field at the rear rather than across the garden and driveway, which kept plant movements away from the house and limited reinstatement to a single working corridor.

The completed upgrade delivers 1.76kg of phosphate betterment against the catchment.

Senga’s own assessment of the work:

“Project Engineer Cam tried to do everything he possibly could for us. Not only me, but the men working here — if they wanted something, he went and got it and dealt with it.”

“You left it as well as it could be. It’s going to make a mess, but it will recover. And it is recovering — as you can see, my grass is regrowing.”

Senga’s motivation was not compliance. It was the value of the house her daughter will inherit. She had watched a friend sell a property of a similar age the year before, only for the buyers to survey the septic tank late in the process and negotiate a five-figure reduction against an agreed price.

“As I’m an elderly lady, and I’ve only got a daughter left when I go, I thought, this is something I should do. I don’t want her to have the bother of it, or lose the money on it.”

The Outcome

A 1950s septic tank decommissioned and replaced with a Graf One2Clean treatment plant creating 1.76kg of phosphate betterment delivered in the River Parrett catchment, evidenced and attributable.
No cost to the homeowner, and a property de-risked ahead of any future sale
Delivered end to end by WCI — scheme administration, survey, specification, installation and reinstatement under one contract