Rainwater Harvesting System Repair: Fix Leaks, Diverters and Pumps

Last updated: October 2026 · Written by the LawnVibe editorial team.

When a rainwater system stops working, the fault is usually in one of a few places: a leaking fitting, a cracked barrel, a gutter or diverter that is not sending water in, an overflow that is sending water the wrong way or a pump that will not run. This rainwater harvesting system repair guide walks through each problem, how to diagnose it and how to fix it.

If water will not come out of the barrel, see rain barrel not draining. To prevent problems, follow our rainwater harvesting system maintenance checklist.

Rainwater harvesting system repair: diagnosis table

Fixing leaking fittings

Leaks at the spigot, overflow port or linking fittings are the most common repair.

1. Drain water below the leaking fitting.
2. Unscrew the fitting and check the washers on both sides of the barrel wall.
3. Replace cracked or flattened washers.
4. Wrap the threads with thread seal tape, three or four turns in the direction of the thread.
5. Reinstall, hand-tight plus a quarter turn.
6. Refill partway and check for drips.

If the hole in the barrel has cracked or widened, use a bulkhead fitting with a locknut and gaskets on both sides.

Repairing a cracked barrel

Small cracks high on the barrel can sometimes be patched. Clean and dry the area, roughen it lightly with sandpaper and apply a plastic repair kit or sealant rated for the barrel material, following the product directions. Many plastics, especially polyethylene used in rain barrels, are hard to bond, so patches may not hold under pressure. Cracks near the base, long splits or brittle, chalky plastic usually mean the barrel should be replaced, because a full barrel holds hundreds of pounds of water.

Barrel not filling after rain

1. Check gutters for leaves and debris.
2. Check the downspout for blockages by running a hose into the gutter.
3. Check the diverter. Make sure it is in fill mode, not winter mode, and that its hose is clear.
4. Check diverter height. If it sits lower than the barrel inlet, water cannot rise into the barrel.
5. Check leaf screens at the downspout and barrel inlet.

Fixing a diverter that does not work

Diverters fail in a few predictable ways:

• Clogged with leaves. Remove the diverter insert or cover and clear debris. Add a leaf screen above it.
• Set too low. The diverter must sit at or slightly above the top of the barrel so water backs up into the barrel and then continues down the spout when full. If it is lower than the barrel inlet, the barrel never fills past that level. Move it up the downspout.
• Hose kinked or blocked. Straighten and flush the connecting hose. Use a short, wide hose.
• Winter setting left on. Many diverters have a switch or cap for winter. Set it back to fill mode in spring.
• Wrong size for the downspout. A diverter made for a different downspout shape or size can let water bypass it. Use the correct model or adapter.
• Cracked insert. Plastic diverters can crack from freezing or UV. Replace the insert.

If you are replacing a diverter, our review of the top gutter diverter kits compares options for homes, sheds and greenhouses.

Fixing a first flush diverter

If the first flush chamber stays full between storms, its slow-drain valve is blocked and it will stop diverting dirty water. Unscrew the end cap, clean the drain valve and filter, rinse the chamber and check the ball or float moves freely. If water bypasses the chamber entirely, check that the ball is seating properly and replace a worn seal.

Fixing leaking gutters and downspouts

Leaks upstream mean less water reaches the barrel and can cause damage to fascia boards and foundations.

1. Clean the gutter so you can see the leak.
2. Dry the area.
3. Apply gutter sealant to leaking seams and end caps.
4. Patch small holes with a gutter patch or flashing and sealant.
5. Tighten or replace loose brackets so the gutter does not sag.
6. Check the slope toward the downspout and adjust brackets if water pools.
7. Reattach downspout sections that have separated and secure them with screws.

Fixing a pump that will not work

1. No power: check the plug, reset the GFCI outlet and inspect the cord for damage.
2. Float switch stuck: free the float so it can rise with the water. Make sure it is not tangled with the cord or wedged against the barrel wall.
3. Water too low: the pump shuts off to protect itself. Wait for rain or top up.
4. Runs but no water: clean the intake screen, straighten the hose and check for an air lock. Some pumps need priming.
5. Weak flow: clean filters, shorten the hose and check that the pump is rated for the head height.
6. Noisy or overheating: turn it off. It may be running dry or the impeller may be damaged.

Replace pumps that still fail after these checks, or contact the manufacturer if under warranty.

Fixing overflow problems

Clear the overflow port and attach a hose or downspout extension that carries water several feet from the foundation. If the barrel overflows every storm, link a second barrel.

Fixing linked barrels

When barrels are linked, problems often appear at the connections. If water does not move from one barrel to the next, check that the linking hose is not kinked, that the ports are clear of leaves and sediment and that the barrels are level with each other. Leaks at linking fittings are fixed the same way as spigot leaks: drain, replace washers, rewrap threads and reinstall. If one barrel has been replaced with a different model, the ports may be at different heights, so adjust the base or use a different port.

Fixing a leaning or sinking base

A barrel that leans puts stress on its fittings and can eventually tip. Drain the barrel completely before working on it. Remove the stand or blocks, add and compact a layer of gravel, reset the blocks or pavers and check with a level in two directions. For larger tanks, a concrete pad or a compacted gravel pad with a solid edge gives the best long-term support.

Repairing screens and lids

Torn screens let in mosquitoes, leaves and small animals. Cut a new piece of fine mesh slightly larger than the opening and secure it with the original ring, a hose clamp or exterior-grade adhesive. Replace warped or cracked lids, since a lid that does not seat properly lets in light and debris. Screw-down or locking lids are safer around children and pets.

Fixing freeze damage

If a barrel was left full over a hard freeze, check it carefully in spring. Look for splits along seams and near the bottom, cracked spigots and fittings and bulges in the walls. Fill the barrel partway with a hose and watch for leaks before reconnecting it. Replace cracked spigots and fittings, and replace the barrel if the walls are split. Damaged pumps that were left in water over winter often fail; test them in a bucket before putting them back in service. To avoid repeat damage, drain and store barrels before freezing weather each year.

Fixing leaks in hoses and drip lines

Hoses, soaker lines and drip tubing connected to a barrel can also fail. Cut out damaged sections of garden hose and join the ends with a hose mender sized to the hose. Replace cracked hose fittings and washers. For drip tubing, use a coupling to replace a damaged section and goof plugs to close holes from removed emitters. Flush lines after any repair to clear debris that entered while the line was open.

Testing after repairs

After any repair, test the whole system before relying on it. Run a garden hose into the gutter above the downspout to simulate rain and watch water travel through the gutter, downspout, diverter and into the barrel. Check every fitting for drips, confirm that overflow leaves through the correct route and draw water from the spigot to check flow. If you use a pump, run it until the float switch turns it off. Fixing a missed leak now is much easier than after the barrel is full, when a repair means draining hundreds of pounds of water first.

Tools for common repairs

• Adjustable wrench and pliers
• Thread seal tape
• Spare washers, O-rings and gaskets
• Bulkhead fittings in common sizes
• Gutter sealant and patch kit
• Fine mesh screen and hose clamps
• Hose menders and drip couplings
• Utility knife and drill with hole saw
• Spirit level for resetting barrel bases
• Work gloves and safety glasses

When to repair and when to replace

Repair is worth it for washers, fittings, spigots, screens, diverters and minor gutter leaks, which are cheap and quick to fix. Replace the barrel if it has large cracks, cracks near the base, brittle plastic or repeated leaks around fittings that no longer seal. Replace a pump if it fails after cleaning and basic troubleshooting. Replacing a barrel is usually inexpensive compared with water damage from a failure. When you replace one, choose an opaque, UV-resistant model with brass fittings for longer life.

Safety when repairing

• Drain barrels before moving them or working on the base.
• Unplug pumps before touching them or reaching into the barrel.
• Use a stable ladder with a helper when working on gutters.
• Wear gloves when handling sludge and roof debris.
• Keep lids secured after repairs.

The EPA offers guidance on rain barrels and other ways to manage stormwater at home.

The bottom line

Most rainwater harvesting system repair jobs are simple: replace washers and rewrap threads on leaking fittings, patch small cracks or replace badly damaged barrels, clear gutters and diverters when barrels stay empty, reroute overflow and troubleshoot pumps by checking power, floats and intakes.

Frequently Asked Questions