When installing a soakaway—whether for rainwater, grey water, or a septic system—choosing the correct distance from your house is critical.
Placing a soakaway too close to a building can lead to serious problems, such as:
❌ Foundation damage – Waterlogged soil can weaken the building’s structural integrity.
❌ Dampness and mold – Excess moisture can seep into walls and basements.
❌ Flooding issues – A poorly placed soakaway can result in standing water near the house.
❌ Legal violations – Many countries have specific building regulations that dictate the minimum soakaway distance from structures.
So, how far should a soakaway be from a house? The general guideline is at least 5 meters (16 feet), but depending on the type of soakaway and soil conditions, you may need to place it even further away.
Let’s break it down step by step.
What Is a Soakaway and Why Does Distance Matter?
A soakaway is an underground drainage system that allows water to gradually disperse into the surrounding soil. It prevents waterlogging, surface runoff, and excess moisture accumulation near buildings.
Soakaways are commonly used for:
✅ Rainwater drainage (from gutters, driveways, or stormwater runoff).
✅ Grey water disposal (filtered wastewater from sinks, showers, and washing machines).
✅ Septic system drainage fields (dispersing treated wastewater into the ground).
However, placing a soakaway too close to a house can cause serious structural and environmental problems, including foundation damage, soil instability, and water pollution.
Recommended Distance Between a Soakaway and a House
The required distance depends on the type of soakaway and soil conditions. Here’s a general guideline:
| Type of Soakaway | Minimum Distance from House | Additional Considerations |
|---|---|---|
| Rainwater soakaway | 5 meters (16 feet) | Must be in free-draining soil. |
| Grey water soakaway | 5-10 meters (16-33 feet) | Requires pre-filtering to prevent blockages. |
| Septic tank soakaway (Drainage Field) | 10-15 meters (33-50 feet) | Must pass a percolation test to ensure soil absorbs effluent properly. |
| Soakaway near a well, borehole, or water source | 15-50 meters (50-164 feet) | Required to prevent groundwater contamination. |
Why a Minimum of 5 Meters?
🏠 Building regulations in most countries require a soakaway to be at least 5 meters (16 feet) from any structure.
This is because:
✔️ Soil around the foundation needs to stay dry to maintain structural integrity.
✔️ Water can cause erosion, weakening the ground under the house.
✔️ Dampness can lead to mold and internal water damage.
For larger soakaway systems, septic drainage fields, or poor draining soil, a greater distance is required.
Factors That Affect Soakaway Placement
Choosing the right distance isn’t just about meeting legal requirements—it also depends on site conditions, soil type, and the type of soakaway system.
1. Soil Type & Permeability
- Sandy soil drains quickly, so a 5-meter distance is usually sufficient.
- Clay soil drains poorly and can cause water to pool, so a soakaway should be placed at least 10 meters away.
- Loamy soil offers moderate permeability, making it an ideal drainage environment.
💡 Perform a percolation test before installing a soakaway to determine how well the ground absorbs water.
2. Depth of the Soakaway
- Shallow soakaways (<1 meter deep) should be at least 5 meters away from buildings.
- Deep soakaways (>2 meters deep) should be placed further away (10+ meters) to prevent underground water from weakening building foundations.
3. Proximity to Other Structures
- Avoid placing a soakaway near driveways or patios (as water can cause shifting or sinking).
- Keep it away from tree roots, which can invade the drainage system and cause blockages.
4. Proximity to Water Sources
- A soakaway must be at least 15 meters (50 feet) away from a water well or borehole.
- This ensures no contamination of drinking water from grey water or septic waste.
In some areas, the required distance may be as much as 50 meters (164 feet) for large septic soakaways.
Legal Requirements & Building Regulations
United Kingdom (Building Regulations Part H)
✔️ A soakaway must be at least 5 meters from a building.
✔️ A septic drainage field must be at least 10 meters from a house and 15 meters from a watercourse.
✔️ A percolation test is required to confirm the site is suitable for a soakaway.
United States (EPA & State Regulations)
✔️ Rainwater soakaways should be at least 5-10 feet from structures.
✔️ Septic systems must be 50+ feet from wells and 10-25 feet from homes.
✔️ Some states require a permit before installing a soakaway.
Australia & Canada
✔️ A minimum distance of 5 meters is required for rainwater soakaways.
✔️ 10+ meters is required for septic or grey water soakaways to prevent groundwater contamination.
📌 Always check with local authorities before installing a soakaway to ensure compliance.
What Happens If a Soakaway Is Too Close to a House?
🚨 If a soakaway is installed too close to a house, serious problems can occur:
❌ Foundation Damage – Waterlogged soil can weaken the ground under the house, leading to cracks and shifting.
❌ Damp & Mold Issues – Excess moisture in the soil can seep into basement walls, causing rising damp.
❌ Flooding Risk – Poorly drained water can pool near the house, leading to property damage.
❌ Blocked or Failed System – If a soakaway gets overloaded, it can clog, stop working, and require costly repairs.
Best Practices for Soakaway Placement
💡 To ensure your soakaway works efficiently and safely, follow these guidelines:
✔️ Place it at least 5 meters from any building (or further for large systems).
✔️ Check soil permeability with a percolation test.
✔️ Avoid placing it near driveways, patios, or tree roots.
✔️ Follow local regulations for septic soakaways and water source protection.
✔️ Ensure proper drainage design to prevent blockages and oversaturation.
Final Answer: Recommended Distance Between a Soakaway and a House
🏠 At least 5 meters (16 feet) for rainwater soakaways.
🚰 At least 10 meters (33 feet) for grey water or septic soakaways.
💧 At least 15 meters (50 feet) from wells or water sources.
📌 Check your local building regulations before installation to avoid legal and environmental issues.
💡 By following these guidelines, you can ensure your soakaway system operates efficiently while protecting your home from water damage!