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Category · Rainwater tanks – collect rainwater for garden, house & industry

Rainwater tanks 50 to 10,000 litres – garden butts, house storage & flat storage Twinbloc®

Rainwater tanks for every need: simple garden butts and rain barrels from 50 litres, slim DEHOUST garden tanks up to 1000 litres, modular Roth house storage tanks for garden irrigation and toilet flushing, and the underground Roth Twinbloc® flat storage tank (1500–10,000 L, car-driveable, connectable) for professional rainwater use in the house and business.

✅ 50 to 10,000 litres ✅ Above- & below-ground ✅ Twinbloc® car-driveable ✅ DEHOUST · Roth · delivery time 1–5 days

Garden butts & garden tanks

Simple above-ground rainwater collectors for garden irrigation – from small rain barrels (50 L) through classic DEHOUST plastic butts (150–220 L) to larger garden tanks (500–1000 L). Slim, tall design, UV-resistant PE, simple connection to the downpipe. No installation, no fitting – ready to use immediately.

Roth house storage – for garden & house

The Roth house storage tanks (750–2000 L) are designed for domestic rainwater use – not only for the garden, but also for toilet flushing and laundry water. Available as a base (with a DN 50 inlet and overflow siphon) or extension, installable above and below ground. Green PE with steel bands, opaque to prevent algae growth.

Roth Twinbloc® – underground & car-driveable

The Roth Twinbloc® flat storage tank is designed for full underground installation – with 1500 to 10,000 litres capacity, car-driveability, a DN 600 dome shaft and an optional integrated filter basket. Several Twinbloc tanks can be connected via a DN 100 sewer pipe. The standard solution for professional underground rainwater use in residential construction.

Roth industrial storage – for trade & businesses

The Roth industrial storage base tanks (2000 L and 3000 L) are flat-rectangular large storage tanks with a DN 100 inlet and overflow siphon for commercial rainwater use in car washes, nurseries and businesses. Modularly expandable with additional tanks. Also available in the Industrial Water Tank category.

The right rainwater tank for your needs

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Which tank for which purpose?

Garden irrigation only: rain butt or garden tank (50–1000 L) – cheap, above-ground, no installation. Garden + toilet + washing machine: Roth house storage (750–2000 L) with a domestic waterworks unit – semi-professional. Full rainwater use in the house: Roth Twinbloc® underground (1500–10,000 L) with filtration and pressure pump – professional system. Trade and industry: Roth industrial storage base.

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How much volume do I need?

As a guide value: 1 m² of roof area supplies about 0.8 litres of usable water per litre of precipitation. A house with a 100 m² roof and 600 mm annual precipitation: about 48,000 litres/year = 130 litres/day. For pure garden irrigation, 500–1500 L is enough to bridge dry periods. For toilet + garden in a single-family house: 2000–5000 L. For full house supply: 5000–10,000 L.

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Why green or black PE?

Algae need light to grow. Transparent or light-coloured tanks encourage algae blooms – the water becomes cloudy and smells. Green PE (Roth garden and house storage): opaque, prevents algae growth, visually unobtrusive in the garden. Black PE (AquaBank®): also light-tight. Both colours fulfil the same protective function – no chemical algicide use needed.

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Twinbloc® – what does car-driveable mean?

After installation in the ground, the Roth Twinbloc® can be driven over by cars – the tank withstands the loads of a passenger car without deformation. This also allows installation under driveways, parking areas and garden entrances, where no free space has to be sacrificed for the tank. The standard Twinbloc® is not designed for truck loads – for that there are heavy-duty variants.

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Connecting several Twinbloc® tanks

Several Twinbloc® containers can be connected to existing drilling surfaces with a DN 100 sewer pipe – the water equalises between the tanks. The Roth connection set (hole saw + two special seals DN 100) enables easy connection on site. This allows the capacity to be increased step by step without having to replace the entire tank.

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Filter – inlet filter and filter basket

Rainwater from the roof contains leaves, bird droppings and fine dirt – without filtration these get into the tank and worsen the water quality. The Twinbloc® is optionally available with an integrated filter basket in the dome shaft. For house supply (toilet, laundry), an external inlet filter is additionally recommended. The house storage tank has a DN 50 inlet with inlet calming.

Frequently asked questions about rainwater tanks

The simple formula: roof area (m²) × precipitation (mm) × 0.8 = usable water (litres). The factor 0.8 accounts for evaporation, filter losses and roof soiling. Example: 120 m² roof × 600 mm annual precipitation × 0.8 = 57,600 litres/year = about 160 litres/day. For pure garden irrigation, however, the water is needed above all in summer, when little rain falls – which is why a large tank as a buffer makes sense. The average annual household in Germany has about 500–700 mm of precipitation (very variable by region).
Yes – the use of rainwater for toilet flushing and the washing machine (coarse laundry) is permitted in Germany. Requirements: the pipe system for rainwater must be run completely separately from the drinking-water supply (no return flow into the drinking water). All extraction points must be marked as "Not drinking water". No permit is required, but a notification obligation to the water supplier (§ 13 TrinkwV) applies. For drinking water and cooking, untreated rainwater is not suitable.
Roth garden storage: simple above-ground tank for garden irrigation – no overflow siphon, no building-services connection. Roth house storage: with a DN 50 inlet, overflow siphon, small-animal barrier – for garden and building-services use (toilet, washing machine), above or below ground. Roth Twinbloc®: fully buried, car-driveable, up to 10,000 L, DN 600 shaft, filter basket optional – professional rainwater system for house and trade. The more demanding the use, the more treatment and system technology is needed.
For simple garden irrigation by hose: yes, a simple submersible pump is enough. For toilet flushing and the washing machine in the house: a domestic waterworks unit (pressure pump with pressure vessel) – this builds up the necessary water pressure so that the rainwater can be used like tap water. The pump's suction basket should be installed floating in the tank in order to extract the clearest water from the middle of the tank (not from the bottom with sediment).
Only if the rainwater is fed into house installations (toilet flushing, washing machine): yes – under § 13 para. 4 TrinkwV (Drinking Water Ordinance), the operation of a rainwater system connected to the house installation must be notified to the responsible water supplier. For pure garden irrigation from an above-ground tank (garden butt), no registration is required. The notification is simple, costs nothing and serves to protect the public drinking-water network from back-contamination.
Yes – after installation, the Roth Twinbloc® is car-driveable according to the manufacturer's specifications. This means: it withstands the loads of a passenger car without deformation. The prerequisite is correct installation in accordance with Roth's installation guidelines – in particular a suitable load-bearing layer beneath the tank, correct backfilling and sufficient cover (minimum installation depth). For truck crossings or heavy construction-site traffic, special heavy-duty variants or reinforced installation measures are required.

The right rainwater tank for your house or business

Our specialist team advises you free of charge – on volume, type of installation, filtration and the optimal solution for your rainwater use.

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