What is the law regarding water runoff into gardens of properties built at the bottom off, or on a hill, or slope lower than neighbouring properties.


THE LAW.  There is a right to natural drainage. This means that water flowing naturally across the surface  is permitted to flow downhill  into your garden and from your garden to neighbours lower down.

The neighbour or yourself should not increase or channel the flow of water in such a way as to redirect or increase the natural flow or cause damage to yours or your  neighbour's land.

What can I do to stop my garden becoming waterlogged by water run-off from neighbours .

The obvious solution is to install a French drainage system described here to dry out the entire garden and channel the water into the drainage system.

However, there are two other things you can do to stop water from neighbours running into your garden. 

  1. Block the water runoff, using a simple wall,
  2. Catch and channel the water runoff  away from your garden, using a basic French drain.

I have described both ways below.


1. Blocking the water runoff from your neighbours garden is not neighbour friendly as it will cause the water to back-up into your neighbours garden. 

However!!!  Assuming; 

  • The excess water is caused by green-lawn-man over watering his lawn.
  • Changes to the neighbouring garden surface using non-permeable materials meaning rainwater has nowhere else to go,
  • Deep footings to an extension to the property redirecting the flow into your garden.
  • Emptying a pool or hot-tub is sending all the dirty water your way.
  • You have tried reasoning and explaining the problem.
  • The neighbour is not a violent nutter.

Neighbour friendly or not, it is a solution I have used.

1;How to build a wall to block water run-off from neighbouring gardens

Key points;

  • You can use any waterproof material to build a water blocking wall. My preferred material is Breeze Blocks (Cinder blocks in the United States) backed with a waterproofing membrane.
  • Water will flow down even the slightest slope and will follow the wall to an exit point. So it is important to plan the route the water blocking wall will take and where it will end. Preferably not back into your garden, but into a drain or back into the inconsiderate neighbours garden.
  • The blocks need to be sunk about two thirds into the soil to stop seepage under the wall. For a light trickle flow lay the blocks long side down or Short side down for light to heavy flow and two blocks high for heavy flow.
  • If you have a boundary fence that belongs to you, it is a good ideal to raise it so it's just of the ground, to prevent it rotting as the water rises and backs up,

Building a water runoff blocking wall.

Start by digging a trench as close to the boundary as you can running the length of the boundary to the discharge point. Preferably not back into your garden, but into a drain or the troublesome neighbours garden. Line the bottom of the trench with concrete, leave it to firm-up (follow instructions on the bag) and set the blocks. Ensuring about one third of the block is above ground level to form a channel. Fix the waterproofing membrane on the neighbours side of the wall according to the instructions on the roll.

Back fill the trench on your side.


2; How to make a trench to catch and channel the water runoff away from your garden.

Key points;

  • You will need 20mm clean gravel and a landscape fabric to wrap around the gravel to keep earth out and allow water through.
  • Water will flow down even the slightest slope and will percolate through the gravel to an exit point. So plan the route the drain will take and where it will end. Preferably not into your garden, but into a drain or back into the troublesome neighbours garden.

Building the catch and drain trench.

Dig a trench along the length of the boundary with the neighbouring garden towards the place the water will drain too. This type of gravel drain need only be about 6" wide and 12" deep.

Before filling with gravel, line the trench with landscape fabric to keep earth out of the gravel and allow water to percolate through easily.

Fill the trench with  20 ml coarse gravel . Wrap the fabric over the top of the gravel and hold the overwrap in place with gravel or a few larger stones, For more detail about constructing French drains visit my garden drainage page.

There's better way to deal with rainwater runoff

create a rain garden and help the environment

This article will explain

  • What a rain garden is and what it's used for.
  • Where to site it.
  • Suitable plants to plant in a residential rain garden.
  • How it is different from a bog garden.
  • How to build/create a rain garden.