Instant
01 · Ask
Ask the AI a follow-up
Got more questions about rainwater Harvesting System? Describe the bit you're unsure about — the AI explains options, sequencing and what to ask the drain specialist.
Install rainwater harvesting.
Rainwater collected from roof to underground tank — for WC flush, washing machine and garden.
✓ Updated May 2026✓ Free quotes✓ Vetted pros
20,000+UK homeowners
50,000Quotes sent
Keep going
Hire a drain specialist. CCTV first, dig only if needed.
You've read the brief on rainwater Harvesting System. Now lean on us to find the right drain specialist — and stay in control of the job.
Free
02 · Read the brief
Walk in informed
Costs, timelines, pitfalls and the right questions to ask before any drain specialist starts on rainwater Harvesting System.
60 seconds
03 · Compare
Compare 3 drain specialist quotes
Itemised quotes from up to 3 local drain specialists on rainwater Harvesting System — so you can compare like-for-like, not lump sums.
✦
Get drain specialist quotes Ready when you are
Enter your postcode and get free quotes from local pros.
Top tips
Hiring a drain specialist, without the regret.
Four moves that separate a smooth job from a nightmare.
Tank too small
Sized to roof and consumption. Calculate carefully. 5,000L typical UK home.
Algae growth
Sunlight on tank water grows algae. Use opaque underground tanks.
Cross-contamination
Without proper backflow prevention, rainwater can backflow into mains. WRAS approval essential.
Filtration costs
UV filtration for indoor use adds cost. Outdoor use only avoids this.
Costs & timeline
Know what it costs. Know when it ends.
Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
Garden-only system (above-ground)1,500-3,000L tank
£800–£2.5k
Underground tank system5,000-10,000L
£2.5k–£5.5k
Full house system (toilets + garden)Large tank + plumbing
£4.5k–£8.5k
Tank only (1,500L garden)DIY-friendly
£200–£800
Smart pump systemPressure pump
£500–£2.5k
Combined rainwater + greywaterMaximum reuse
£6.5k–£14k
!
Quote spread is typically ± 18% — always get 3 quotes.
At a glance
Infographic · VideoThe Drain Specialist briefing.
Infographic
Drain Specialist quick-view
Video guide
Drain Specialist explained
Rainwater harvesting collects roof rainwater for reuse — garden watering, toilet flushing, car washing. Expect to pay £1,500–£8,500 for UK rainwater harvesting system.
What Does the Work Involve?
Tank installed (above-ground or below). Roof rainwater piped to tank via filter. Pump distributes water for use. Smart controls maintain levels. Mains backup for empty periods. Greywater integration possible. Garden hose, toilet flushing, washing machine all potential uses.
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| Garden-only system (above-ground) | 800 | 2,500 | 1,500-3,000L tank |
| Underground tank system | 2,500 | 5,500 | 5,000-10,000L |
| Full house system (toilets + garden) | 4,500 | 8,500 | Large tank + plumbing |
| Tank only (1,500L garden) | 200 | 800 | DIY-friendly |
| Smart pump system | 500 | 2,500 | Pressure pump |
| UV filtration system | +£300 | +£1,200 | For toilet flushing |
| Combined rainwater + greywater | 6,500 | 14,000 | Maximum reuse |
How Long Does It Take?
Above-ground system: 1-2 days. Underground tank: 3-5 days. Full house: 1-2 weeks.
DIY or Professional?
Above-ground garden: DIY-friendly. Underground/whole house: specialist installer.
Choosing the Right Tradesperson
Specialist rainwater installer or plumber. WRAS-approved equipment for toilet/washing. Brands: Wisy, Graf, Fineflora.
UK Regulations
Water Supply (Water Fittings) Regulations 1999. WRAS approval for any indoor use. Backflow prevention essential. Building Regs Part G for indoor use.
Common Problems
- Tank too small: Sized to roof and consumption. Calculate carefully. 5,000L typical UK home.
- Algae growth: Sunlight on tank water grows algae. Use opaque underground tanks.
- Cross-contamination: Without proper backflow prevention, rainwater can backflow into mains. WRAS approval essential.
- Filtration costs: UV filtration for indoor use adds cost. Outdoor use only avoids this.
Frequently Asked Questions
Garden only or whole house?
Garden only: cheaper, simpler, no plumbing changes. Whole house: bigger investment, more savings, plumbing integration.
How much will I save?
Annual saving £50-£200 on water (depending on meter rate). 8-15 year payback typical. Environmental benefit too.
How big a tank?
Garden only: 1,500-3,000L. Toilets and garden: 5,000-10,000L. Whole house (including washing): 10,000L+.
Above-ground or underground?
Above-ground (water butts): cheap, easy install, smaller capacity. Underground (cellar or garden): more expensive, larger capacity, hidden.
Filter requirements?
Particle filter for garden. UV disinfection for toilet flushing. Full treatment for any potable use (rare).
Pump and pressure?
Standard pressure pump (3 bar) for typical use. Higher pressure for hose/garden tap. Variable speed for efficiency.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
NEWAI Trade Assistant
Got more questions
about drain specialist?
Ask follow-ups in plain English. The AI explains options, sequencing and what to ask the drain specialist — so you walk in informed.
I'm planning a job. Should I be looking for a drain specialist?
Sounds like a job for drain specialist. Tell me what you're trying to do — I'll walk you through costs, timeline and what to ask before they start.
FREE QUOTES60 SECONDS
Keep reading
VIEW ALL DRAIN SPECIALIST GUIDES →More drain specialist guides.
Guide
Emergency Drain Clearance Guide
A blocked drain is more than just a nuisance; it is a potential health hazard and a risk to your property’s structural integrity. Whether it is a slow-draining ...
READ GUIDE →GuideSeptic Tank Repair Cost & Guide
For many rural UK homeowners, a septic tank is an essential piece of infrastructure that remains out of sight and out of mind until something goes wrong. Howeve...
READ GUIDE →GuideCCTV Drain Survey Cost & Work Guide
A CCTV drain survey is the most effective way for UK homeowners to identify hidden issues within their drainage system without the need for disruptive excavatio...
READ GUIDE →GuideDrain Relining Process & Cost
Drain relining, often called "no-dig" technology, is a modern method of repairing damaged pipes without the need for disruptive excavations. For UK homeowners, ...
READ GUIDE →GuideDrainage Survey Cost & Work Guide
A drainage survey is often the only way to see what is happening beneath your property. Whether you are buying a new home or dealing with a stubborn blockage, a...
READ GUIDE →GuideDrain Repair Process Guide
A faulty drainage system is one of those household issues that remains invisible until it becomes a crisis. Whether it is a slow-draining sink, a persistent fou...
READ GUIDE →