How Deep Should I Bury My Water Pipe?

When installing an MDPE system in the UK,it's essential to pay attention to how deep it's buried. You can opt for several approaches, such as the no-dig, low dig, and the classic trench methods. This guide focuses on informing you about the required depths for MDPE water pipe.

Determining the correct depth for your blue MDPE:

Getting the depth right for your blue MDPE is key. In the UK, it should sit at a minimum of 600mm from the crown, not exceeding 1350mm from the ground level. Maintain a safe distance of 350mm separation from gas and electricity pipes. Local authorities may have varying guidelines, but they often allow some leeway if you ensure proper insulation.

During burial, provide a minimum 100mm top cover above the pipe, avoiding heavy machinery compaction until a 300mm cover is achieved. Backfill the trench in 300mm layers, prioritizing safety by installing marker tape 300mm above the pipe to warn future excavators or workers.

Considerations before installation:

1. Contact water authorities for project information and guidelines. Refer to the Water Supply (Water Fittings) Regulations 1999. They're the rulebook for installers, owners, and users, dictating what pipes and fittings to use. Seek guidance from your local water authority on the installation of new supply pipework.

2. Before excavation, identify the location of cables and pipes from any other nearby utilities.

3. Ensure your trench is wide enough to accommodate MDPE pipes --Your trench should be at least the outside diameter of the pipe plus 250mm wide to let you pack in the side fill just right.

4. For pipes running under buildings, run the water pipe through twinwall ducting and seal it with end caps and, if necessary, expanding foam to prevent vermin and dirt infiltration. Avoid using compression MDPE fittings inside the ducting.

5. Refer to WIS 4-08-01 for details on bed and fill materials. In some cases, MDPE may be laid directly onto the trimmed trench bottom if the soil is uniform, fine-grained, and free from large stones and flints. In other situations, you should dig the trench to a depth that accommodates a minimum 100mm layer of gravel, crushed stone, or coarse sand. If preferred, a blend of sand and gravel is acceptable, as long as the gravel size does not exceed 20mm.

6. Rules may vary for preventing freezing; some projects may require a trench with space for 100mm of bed stone, using gravel with a maximum size of 20mm. If the soil is uniform enough, you might get away without a gravel bed.