A drainage system is a simple and versatile construction for draining water from problem areas in your garden or from the cellar. The process is quite simple, it only requires preparation and planning, the right tools and materials and a little practice with do-it-yourself. Start with the first step below to find out how to build a drainage system.
Steps
Part 1 of 2: Planning and Preparation
Step 1. Check the subsoil
Before building a drainage system in a specific area, make sure where all the underground cables, pipes and other utilities are that could make it dangerous to dig in that precise point.
- Check with municipal authorities and various agencies that you have free space to build your drainage system.
- Also be sure to plan your drainage route well so that it is always at least three feet from walls or fences, and try to avoid posts, bushes or tree roots.
Step 2. Check for any problems with the zone or runoff
There are municipal regulations governing where you can dig.
- In order to complete your project you will need to contact the local authorities and the competent offices. It may seem crazy, but even the smallest job may require the authorities to sign. Make sure you know the rules in your area before planning anything.
- You will also need to determine whether or not your drainage system will cause problems for your neighbors in terms of groundwater runoff. Running too much water into someone else's soil can lead to legal consequences.
- Ideally, the drainage system should drain into an unused portion of land, away from buildings and in sandy soil that allows water to filter easily.
Step 3. Find a downhill slope
To function well, the drainage must be built into a slightly downward slope. This will allow the water to slide away from the problem area thanks to the force of gravity alone.
- If there are no natural slopes, you can create one by going deeper and deeper as you dig the ditch. Experts recommend a 1% slope for drainage to be effective.
- Use paint to mark the path of the ditch, then use battens, wire and a level to set the inclination from one side of the ditch to the other.
- If you are unable to find the exact slope of your drain on your own, you can ask a surveyor or other professional to help you find the size and position of the drain. You can still do it yourself, but you will be more comfortable if someone else has signed the project.
Step 4. Get tools and materials
To build a drainage system you will need to have a number of tools and materials. You will need:
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A roll of water permeable fabric:
this will help keep the pipes clean and prevent them from clogging by preventing soil, debris and roots from entering the drain.
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A perforated plastic drain:
the diameter will depend on the extent of the problem and the size of the ditch. You can choose between flexible drainage pipes, or more rigid PVC pipes (more expensive, but more resistant and less prone to becoming clogged).
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Gravel for clean drainage:
the number of bags depends on the size of the project. Use an online calculator to get an estimate based on the depth and width of the trench you have designed.
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Tools:
if you plan to dig by hand, you will need a shovel. Otherwise you will need a digging tool or you can hire an operator who can use an excavator.
Part 2 of 2: Building the Drainage
Step 1. Dig the ditch
Digging the ditch is the least complicated part of building a drainage system, but it's the hardest! Get help from a friend or family member if possible.
- The width and depth of the drainage you are digging will depend on the severity of the problem and the tool you are using. However, most are 15 cm wide and 35 to 50 cm deep.
- Digging tools will help you dig wider (ideal for more serious problems) and get the job done in half the time. However, the use of these tools will increase the cost because you will have to pay the rent and you will have to buy more gravel to fill the excavation.
- The same is true if you want to hire someone to operate an excavator; these machines dig very deeply and make larger holes resulting in higher costs.
- As you dig, always check the depth of the ditch to make sure it has a constant slope.
Step 2. Line the ditch with fabric
Once you have finished digging, you will need to line the ditch with water-permeable fabric.
- Leave about 20 cm of extra fabric on both sides of the ditch.
- Hold the excess fabric on the sides with pins or nails.
Step 3. Add the gravel
Put about 6 cm of gravel at the bottom of the ditch, above the fabric.
Step 4. Put the pipes down
Place the perforated pipes in the ditch, on top of the gravel. Make sure the drainage holes are facing down, this will give you more drainage.
Step 5. Cover the pipes
Add gravel over the pipes, until there is 6 to 10 cm between the gravel and the top of the ditch.
- Free the excess fabric and fold it over the gravel layer.
- This will prevent debris from entering the drainage while still allowing the passage of water.
Step 6. Fill the ditch
Fill the rest of the ditch with loose earth. At this point you can finish it however you like:
- You can put the sod on the top, replant the grass or even cover everything with large decorative stones.
- Some put the pipes down by making a slight bend, so that when finished it may look like some kind of drawing.
