Experts in Concrete Patio installation

Why Is Water Pooling on My Patio? Drainage Fixes That Work

Standing water on a concrete patio is more than just a nuisance, it’s a warning sign. From slippery surfaces to long-term structural damage, poor patio drainage can cause real problems if left unchecked. Fortunately, most issues can be traced to a few common causes and corrected with the right solution.

In this guide, we break down why patios in the UK often suffer from water pooling, what it means for your garden, and how to fix the problem permanently using drainage systems that actually work.

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Why Water Builds Up on Patios

In the UK’s damp climate, concrete patios are regularly exposed to heavy rainfall. If water isn’t draining properly, the problem usually lies in how the patio was designed or installed. Below are the main reasons water may be pooling on your patio surface.

Incorrect Slope or Gradient

A well-laid patio should have a subtle slope to guide rainwater away from the surface. When the gradient is too flat, or worse, tilting back toward the house, water will naturally collect in low spots. This is one of the most common reasons for standing water, especially on older or DIY patios where levels weren’t carefully measured. A fall of 1:60 (around 16mm drop per metre) is typically recommended to ensure proper drainage across a patio surface.

Blocked or Missing Drainage Channels

Patios that border buildings or sit lower than the surrounding ground often require drainage channels to divert water. Without them, rainfall has nowhere to go and pools quickly. If drains are present but clogged with leaves, soil or debris, they won’t perform properly. Regular maintenance or installing discreet slot drains at key collection points can prevent water buildup and protect your patio from long-term damage.

Sunken or Uneven Slabs

When parts of a concrete patio settle over time, the surface becomes uneven. These dips act like shallow bowls, catching and holding rainwater. This is especially common when the sub-base was poorly compacted or the patio is over 10 years old. Without corrective levelling or relaying of affected areas, pooling will continue after every downpour, gradually wearing away the surface.

Soil and Landscape Conditions

If the ground around your patio doesn't drain well, water may back up onto the concrete even if the patio itself is level. Heavy clay soils common in the UK retain moisture, creating soggy patches. Surrounding flower beds or turf that slope toward the patio can also contribute. Solving these issues may require subtle regrading of the landscape or introducing discreet drainage solutions along the edges.

No Permeable Surface Treatment

Concrete is naturally impermeable, which means it doesn’t absorb water. Without any treatment or drainage system in place, rainfall will sit on the surface until it evaporates. Applying a breathable sealant or switching to a more porous finish can help, but on its own, this won’t solve structural drainage problems. It should be part of a wider drainage strategy.

How to Solve Patio Drainage Issues

Adjusting the Slope

If your patio doesn’t slope away from your home, regrading or relaying may be necessary.
This typically involves removing and re-laying affected areas with the correct fall toward garden beds or drains.
Best for patios with consistent pooling across large flat zones.

Installing Drainage Channels

Slot drains or French drains can be added along key patio edges or where water collects most.
These guide water to a soakaway, garden border, or underground pipe system.
Ideal for patios next to buildings or on sloped plots where water backs up easily.

Raising Sunken Slabs

Individual slabs can be lifted, re-compacted, and re-laid to correct dips and low spots.
Ensures surface water drains evenly and doesn’t sit in shallow puddles after rainfall.
Works well for older patios where only small sections are affected.

Frequently Asked Questions

Flooding is usually caused by improper slope, lack of drainage channels, or compacted soil that doesn't absorb water. Without a clear route for rain to drain away, water pools on the surface and creates puddles after every shower.

Yes. In many cases, drainage channels or soakaways can be retrofitted along patio edges or in problem areas. This often involves cutting into the concrete and installing a discreet system to redirect surface water safely away.

Sealing alone won’t prevent water pooling. It protects the surface from absorbing moisture but won’t change the slope or solve drainage issues. Sealing should be part of a wider solution that includes correcting levels or adding drains.

Not always. If the issue is minor or localised, targeted drainage can be added without removing the entire patio. But if the whole surface is sloping incorrectly or sunken, re-laying may be the most effective fix.

Ensure the patio is laid with the correct slope and on a solid, free-draining sub-base. Keep drains clear, use breathable sealers, and regularly check for changes in levels. Good initial design and maintenance are the best defences.