Quick answer

Biochar filter systems range from £1,000 for simple runoff units to £20,000–£70,000+ for complex engineered solutions. Most farms and estates fall in the £5,000–£15,000 band once proper sizing and design are included.

Below is a practical budgeting framework to help you understand which category your site is likely to fall into.

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Tier 1 — Simple, low‑risk runoff (field drains, tracks, yard edges)

Budget: £1,000–£3,000 per location
When suitable:

• Low, steady flows (<2–5 L/s)
• Mainly sediment + nutrient polishing
• No requirement for guaranteed pollutant removal

Typical costs:

• Biochar media: £400–£700 per m³
• Simple casings/IBCs/DIY structures: £300–£1,000
• Total typical cost: £1,000–£3,000

Rule of thumb: 1–3 m³ of biochar media per discharge point.

Notes: Best for quick wins where the aim is improved water quality without formal performance guarantees.

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Tier 2 — Medium complexity (farmyard runoff, estates, lakes, fisheries)

Budget: £5,000–£15,000
When suitable:

• Known upstream contaminants (slurry yards, wash-down areas, metals, organics)
• Desire for expected performance but not regulatory guarantees
• Moderate or variable flows

What is usually involved:

• 0.5–2 days site assessment (remote or onsite)
• Preliminary sizing and modelling
• Optional sampling
• Media and casing specification

Typical costs:

• Design/scoping: £800–£2,500
• Media (2–8 m³): £800–£5,000
• Units, manifolds, installation: £1,500–£6,000
• Total typical cost: £5,000–£15,000

Notes: This is the range most farms and estates fall into when they want a thought‑through, evidence-based installation.

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Tier 3 — High‑complexity engineered systems (large flows, multi‑input, high compliance risk)

Budget: £20,000–£70,000+
When suitable:

• Flows >20 L/s or highly variable loads
• Sites with EA compliance pressure, SSSI sensitivity, or fishery risk
• Systems requiring multiple treatment stages (settlement → biological → biochar)

What is usually involved:

• 2–5 days investigation & sampling
• Hydraulic and contaminant load modelling
• System layout development
• Specification for contractors
• Optional monitoring plans

Typical costs:

• Design & modelling: £3,000–£10,000
• Media (5–30 m³): £2,500–£20,000+
• Installation by third parties: £10,000–£40,000+
• Total typical cost: £20,000–£70,000+

Notes: These systems behave like small wastewater treatment works. Biochar is one part of a wider train.

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What should I do next?

If you are unsure which tier you fall into, the simplest approach is:

1. Identify your runoff type and scale.
2. Estimate flow (even roughly).
3. Match to the closest tier above.
4. Contact us with a brief description — we can confirm the likely range before any site visit.

This structure helps set realistic expectations while keeping options flexible for early‑stage, evidence‑based design.