With rising water bills and frequent hosepipe bans across the UK, capturing rainwater has become a practical necessity for any gardener. A water butt connects directly to your existing guttering system, collecting roof runoff that would otherwise flow into the drains. The water collected is naturally soft and free of chlorine and added minerals, making it better for your plants and gentler on your soil. Installing a water butt is a straightforward weekend project that pays for itself within one season. For homeowners thinking about broader water management inside the house, our guide on Water Heater Selection And Installation Tank Type Tankless And Heat Pump Water Heaters For Residential Applications covers indoor systems that complement outdoor rainwater harvesting.
Why Your Garden Needs a Rainwater Harvesting System
More UK households are fitted with water meters than ever before, meaning every litre from your tap carries a direct cost. During dry summer months, local water authorities often impose hosepipe bans restricting mains water for garden irrigation. A water butt sidesteps both problems entirely by giving you an independent supply of rainwater. Capturing runoff also reduces demand on treatment plants and cuts the energy used to pump drinking water for non-potable uses. Rainwater is chemically superior for plant health. Tap water in many regions contains calcium carbonate and chlorine that alter soil pH over time, while rainwater is naturally soft and slightly acidic, ideal for ericaceous plants such as rhododendrons, camellias, and blueberries. If you enjoy having instant hot water in the kitchen, you may also find our guide on Instant Hot Water Dispensers What To Know Before You Buy And Install useful for reducing indoor water waste as well.
- Save money: Garden watering accounts for up to 30 percent of summer household water use. A water butt makes that supply free.
- Beat restrictions: Hosepipe bans apply only to mains water. Your stored rainwater is yours to use whenever needed.
- Healthier plants: Soft rainwater encourages deeper root growth and better nutrient uptake compared with hard tap water.
- Reduce runoff: Capturing roof water eases the load on storm drains and reduces local flood risk during heavy rainfall.
Types of Water Butts and What to Look For
Water butts come in a variety of shapes, materials, and capacities. The standard round green plastic barrel remains the most popular choice because it is affordable, durable, and widely available with integrated taps and lids. Slimline models are designed for narrow side passages where space is restricted, typically holding 100 to 200 litres while taking up minimal floor area. For something more decorative, manufacturers produce butts styled to resemble terracotta pots, stone urns, or wooden barrels using rotomoulded plastic that weighs a fraction of the real thing. Genuine oak whiskey barrels can also be repurposed as water butts, though they require a liner or careful sealing to prevent leakage. If you plan to integrate rainwater collection into a broader landscape design, the approach is similar to what you would find in this guide on How To Install A Water Feature That Reuses Rainwater, where stored rainwater feeds ponds or fountains instead of a watering can.
| Butt Type | Typical Capacity | Best Location | Average Lifespan |
|---|---|---|---|
| Standard plastic barrel | 100-250 litres | Against house wall or shed | 10-15 years |
| Slimline tank | 100-200 litres | Narrow passageways | 10-15 years |
| Decorative (terracotta/stone style) | 100-300 litres | Visible garden areas | 8-12 years |
| Oak whiskey barrel (repurposed) | 100-220 litres | Cottage gardens | 5-10 years with care |
| Large storage tank | 400-1000+ litres | Garage side or under deck | 15-20 years |
Every water butt should include a secure lid to keep out leaves, insects, and small animals. If children are present in the home, look for models with child-safe locking lids. A tap at the bottom is essential for filling watering cans. Not all butts come with one pre-installed, so check before buying or budget for a separate tap kit. A sturdy stand is equally important. A full 200-litre butt weighs 200 kilograms, and a purpose-made stand lifts it high enough to fit a watering can under the tap. Alternatively, build a base from dense concrete blocks laid on compacted hardcore.
Tools and Materials You Will Need
Before starting the installation, gather all the necessary tools and components. The most efficient method uses a rainwater diverter kit, which attaches to your existing downpipe and channels water into the butt without requiring you to cut the pipe permanently. For those upgrading their home plumbing infrastructure, the same attention to detail applied in Installing A Water Softener Essential Plumbing Steps For Hard Water Treatment will serve you well here.
- Water butt with lid and pre-fitted tap, or a separate tap kit
- Sturdy stand or concrete blocks to raise the butt to the correct height
- Rainwater diverter kit matched to your downpipe shape (round or square)
- Hacksaw with a fine-tooth metal blade for cutting the downpipe
- Electric drill with a hole saw or spade bit sized for the diverter connector
- Tape measure and pencil for marking cut positions
- Safety gloves and goggles for cutting and drilling
If you have round downpipes, standard diverter kits fit without adapters. Square downpipes require a square-to-round adapter or a diverter designed for square profiles. Measure the external diameter of your downpipe before purchasing.
How to Install a Water Butt with a Rainwater Diverter
The rainwater diverter method is the cleanest installation approach because it allows the downpipe to continue functioning normally once the butt is full. When the butt reaches capacity, excess water simply flows past the diverter and continues down the pipe into the drainage system. Understanding how water flows around your property is also useful when considering roof protection products such as Ice And Water Shield For Roof Valleys Installation, which prevents ice dams from forcing water back under roof coverings.
- Position the stand and butt. Place the stand on level ground against the wall where the downpipe runs. Sit the empty butt on the stand and mark the top edge on the downpipe. Add 3 centimetres above this mark to allow clearance for the diverter.
- Cut the downpipe. Using a hacksaw, cut the downpipe horizontally at the pencil mark. Make the cut as square as possible so the diverter fits flush. Deburr the cut edges with sandpaper.
- Fit the diverter body. Slide the two halves around the downpipe at the cut point. The top section slots into the diverter inlet, and the piece you removed slots into the diverter outlet below. Snap or screw the halves together.
- Drill the butt. Measure 8 centimetres down from the top rim and drill a hole using a hole saw matching the diverter connector diameter. Drill slowly to avoid cracking the plastic.
- Attach the connector. Push the threaded connector through the hole from the outside. Screw the sealing washer and retaining nut onto the connector inside and tighten firmly by hand, then a quarter turn with pliers. Do not overtighten.
- Connect the diverter to the butt. Attach the connecting pipe between the diverter outlet and the butt connector. Ensure the pipe slopes slightly downward so water flows freely.
- Test the system. Fit the lid securely. Run water into the gutter above and confirm it flows into the butt. Once full, check that excess water exits via the downpipe as normal.
Alternative Installation: Direct Downpipe Connection
If you prefer not to use a diverter, you can install the water butt directly beneath a downpipe by cutting the pipe short and feeding it through a hole in the butt lid. This method requires no specialist kit, but once the butt is full the downpipe is effectively blocked and water may spill over the side. An overflow hole near the top fitted with a hose barb and a length of hose directed to a drain or a second butt is therefore essential. For homeowners looking at indoor heating systems as well, the principles of managing water flow in this setup are similar to those explained in How To Install A Combination Boiler Water Heater, where careful pipe alignment determines system efficiency.
Position the butt on its stand and mark the downpipe height directly above the lid opening. Cut the downpipe so it extends 2 to 3 centimetres into the butt through the lid hole. Drill or cut a hole in the lid large enough to accept the pipe, then fit the lid with the pipe passing through. Seal the gap around the pipe with silicone sealant or a rubber grommet to stop debris and mosquitoes from entering. Drill an overflow hole 5 centimetres below the top rim on the opposite side of the butt and fit a hose barb. Attach a hose that runs to a drain, a soakaway, or a second linked butt. This setup is simpler but less flexible than the diverter method, as relocating the butt requires cutting the downpipe again.
Smart Water Conservation in the Garden
Collecting rainwater is only half the battle. Using it efficiently ensures every litre goes further. Hand watering with a can directed at the root zone delivers water exactly where needed, unlike sprinklers that waste a large percentage to evaporation. If you must use a hose, fit a trigger nozzle that stops the flow between plants. Water in the early morning or late evening to minimise evaporation and allow moisture to penetrate before the sun gains strength. Deep, less frequent watering encourages stronger root systems than shallow daily watering. For readers planning bathroom renovations alongside their garden upgrades, careful waterproofing is equally important, and our guide on How To Install Tile Murals In Shower Walls A Complete Technical Guide offers practical advice for wet-area finishes.
- Use a watering can instead of a hose to cut consumption by up to 50 percent
- Fit trigger guns on all garden hoses to prevent wastage between plants
- Water early morning or evening for deeper soil penetration
- Keep borders free of weeds that compete with your plants for moisture
- Mulch around plants with bark chips or compost to retain soil moisture
- Group potted plants together so they shade each other and reduce water loss
Maintaining your water butt is straightforward. Check the diverter inlet once a month during autumn when falling leaves can block the mesh filter. Clean the inside of the butt once a year by tipping it over and rinsing with a dilute bleach solution followed by a fresh water rinse. During winter, drain the butt completely if frost is forecast, because expanding ice can crack the plastic body or split the tap fitting. Store the tap and diverter connector indoors until spring.
Conclusion
Installing a water butt is one of the most cost-effective improvements you can make to your home and garden. It reduces your water bill, protects your plants during hosepipe bans, and cuts the environmental impact of your household water use. The installation requires only basic DIY skills and a few hours of work. Whether you choose the diverter method for its flexibility or the direct connection for its simplicity, the result is a reliable supply of soft, natural water that your garden will thrive on. For a holistic approach to home water quality, read our guide on Complete Guide To Home Water Filtration Systems Types Installation to explore how whole-house filtration can complement your outdoor rainwater harvesting strategy. Every drop you collect is free, sustainable, and better for your garden than anything that comes out of a tap.