Rainwater Tank Installation
Fast, reliable installation is where ViaCon’s corrugated steel rainwater tanks deliver their biggest practical advantage over concrete and modular plastic alternatives. A 100,000-litre steel tank can be installed in two working days; an equivalent concrete tank typically takes two to three weeks. This page covers what to expect when installing an underground rainwater tank on a UK commercial site — from delivery through to commissioning. For sizing guidance, see our rainwater harvesting tank sizing page. For a full system overview, see rainwater harvesting systems.
Underground Rainwater Tank Installation — Step by Step
A standard ViaCon underground steel rainwater tank installation follows five stages:
- Site preparation — excavation to specified depth, levelling of base, bedding with compacted granular fill
- Tank placement — single-lift delivery to final position using standard site crane (no specialist lifting equipment)
- Pipework connection — inlet, overflow and outlet connections completed using mechanical couplings
- Backfill and compaction — granular backfill placed in 300mm layers and compacted around tank to design density
- Commissioning — filter installation, pump connection, pressure testing, controls configuration, handover to M&E contractor
Because steel tanks are self-supporting and traffic-rated (Class 1A), no separate reinforced concrete slab is required above the tank — reducing excavation depth, concrete volume and programme duration.
Cost efficiency
Using rainwater tanks to supplement non-potable water needs can significantly reduce water bills and operational costs, making them a smart investment for businesses and municipalities.
Environmental impact
Our tanks mitigate stormwater runoff by capturing rainwater before it enters drainage systems, reducing flood risks and preventing pollutants from contaminating natural waterways.
Durability and longevity
Constructed from high-grade materials, ViaCon’s rainwater tanks are designed to endure harsh environmental conditions, ensuring a long-term, reliable water source with minimal maintenance.
Versatility
These tanks can be seamlessly integrated into existing systems, making them suitable for a range of projects, from small commercial sites to large industrial complexes. ViaCon’s rainwater tanks adapt efficiently to various water management needs.
Installation Depth and Ground Conditions
ViaCon’s corrugated steel rainwater tanks install from 0.5m cover to 6m cover in standard ground conditions. For high water table sites, the tank is specified with supplementary anti-flotation anchors. For sites with aggressive soil chemistry (sulphate, chloride), ViaCon supplies tanks with enhanced coating specifications to BS EN ISO 12944.
Typical install depths by application:
- Under landscape or amenity areas — 0.5–1.5m cover
- Under car parking — 0.8–1.5m cover, Class 1A loaded lid
- Under yards and access roads — 1.0–2.0m cover, Class 1A loaded lid
- Deep installations (basements, cut-and-fill) — up to 6m cover with structural calculation
Installation Speed and Programme Impact
On UK commercial projects, programme compression is often decisive. A steel rainwater tank installation typically completes in 25–40% less time than an equivalent concrete tank:
- 50,000 L tank — 1 working day for steel, 1–2 weeks for concrete
- 100,000 L tank — 2 working days for steel, 2–3 weeks for concrete
- 250,000 L tank — 4–5 working days for steel, 4–6 weeks for concrete
This compression directly reduces temporary works costs, preliminaries and critical-path exposure — factors that typically determine whether a value-engineering exercise favours steel over concrete.
Installation Compliance and Standards
All ViaCon rainwater tank installations are specified and supplied to:
- BS EN 16941-1:2024 — rainwater harvesting installation standard
- Building Regulations Part H — drainage installation and connection
- Sewers for Adoption 8 — where the scheme integrates with adoptable drainage
- BS EN 752 — drain and sewer systems outside buildings
- DMRB CD 354 — where the installation sits within highway boundary
ViaCon provides pre-installation method statements, lifting plans and risk assessments as standard, and supports main contractors with on-site technical presence during critical phases.
After Installation — Maintenance and Service Intervals
Once commissioned, a ViaCon underground steel rainwater tank requires minimal direct maintenance — the tank structure itself has a 100+ year design life with no active intervention needed. Mechanical components have defined service intervals:
- Pre-tank filter — quarterly inspection, annual clean
- Submersible pump — annual service, replacement at 10–15 years
- Tank sediment check — 5-yearly inspection, sediment removal as required
- Backflow prevention / mains top-up — annual testing (Fluid Category 5 compliance)
ViaCon offers optional UK-wide service and maintenance contracts for specifiers who want single-source accountability across tank and system lifecycle.
Related pages:
Steel: The smarter choice
The strength and sustainability of steel provides durability and lifespan advantages for construction projects.
Value engineering
With consultative problem solving and the versatility of steel, value engineering ensures adaptable, cost-effective solutions.
Case studies
Welcome to the ViaCon design toolkit
We have put together a selection of useful tools, calculators, information and downloadable resources to help you find what you need quickly and get the most out of your ViaCon system.
Contact your local ViaCon representative
ViaCon’s corrugated steel rainwater tanks install in days rather than weeks: typically 1 day for tanks up to 50,000 L, 2 days for 100,000 L, and 4–5 days for 250,000 L — 25–40% faster than equivalent concrete installations.
Yes. ViaCon’s steel rainwater tanks are traffic-rated to Class 1A loading and can be installed under car parks, yards and access roads with 0.8–1.5m cover and a Class 1A-loaded access lid.
No. ViaCon’s corrugated steel tanks are self-supporting and structurally rated for the required loading — a separate reinforced concrete protection slab is not required, saving excavation depth, concrete volume and programme time.
High water table sites require anti-flotation anchors. Sites with aggressive soil chemistry (sulphates, chlorides) require enhanced coating specifications to BS EN ISO 12944. ViaCon’s technical team reviews ground investigation data at specification stage and advises on any required upgrades.