Stormwater System Installation and Rainwater Drainage

A stormwater system starts at the roof and ends at the discharge point. Everything in between must operate by gravity, meaning that gradients and depths cannot be easily altered later – they must be set correctly from the outset.

• Roof gutter system – gutters and downpipes that collect roof water
• Downpipe discharge or ground-level drain that directs water into the piping or away from the wall
• Underground stormwater piping, typically rigid plastic pipes with the correct gradient
• Sand or silt trap that collects sand and debris before it enters the piping
• Gully gratings in driveways, yards, and car parks for collecting surface water
• Inspection chambers that allow for later cleaning and camera inspection of the piping
• Discharge point: public network connection, soakaway system, ditch, or other approved solution

The stormwater drainage solution depends on three factors: whether a public stormwater sewerage system exists in the area, the soil's permeability, and the available space on the property. Choosing the wrong solution means the system works perfectly in dry weather but not at all during heavy rainfall.

This is the most common misunderstanding. A stormwater system collects surface water – from roofs, roads, and yards. Drainage collects water in the soil around the foundation and lowers the groundwater level beneath the building. These are two separate systems with different purposes and different depths.

The most typical mistake is connecting them such that stormwater is directed into the drainage pipes. During heavy rain, the drainage system fills with water and begins to work in reverse: instead of drawing water away from the foundation, it pushes water into the soil around it. The result is a damp basement in a house where drainage is present.

The correct solution is to keep the systems separate and only connect them at the discharge point if technically and permissibly feasible. If you are unsure how your existing system is connected, it can be checked with a camera.

Stormwater system installation involves excavation, and the result remains underground, making costly repairs if done incorrectly. Therefore, preparation is at least as important as the installation itself.

The stormwater solution depends on the property – both in terms of volume and organisation.

Very often, the problem isn't that a system doesn't exist, but that an existing one isn't working. Before building a new one, it's always worth checking what's wrong with the current system – often, cleaning and repairing one section is enough.

• Piping is blocked with sand and sediment because there is no sand trap or it has never been emptied
• Pipe has subsided, forming a water trap where water stagnates and freezes
• Gradient is too shallow or partially reversed
• Downpipe discharge has come loose from the piping, and water flows directly against the plinth
• System is connected to drainage and overflows it during heavy rain
• Gully grating is full of leaves and debris
• Discharge point is blocked, overgrown, or frozen
• System is undersized for the roof and paved area

Winter is the toughest time for a stormwater system. Meltwater comes in large quantities and over a short period, often when the ground is frozen and cannot absorb water. If there is a subsided section or stagnant water in the piping, it will freeze, and the system will stop working precisely when it's needed most.

To prevent freezing, there are two main conditions: sufficient depth and a consistent gradient without water traps. The third is an open discharge point – if the outlet is blocked by ice, even a perfect piping system won't help.

If water is already frozen solid, we can thaw the piping and then use a camera to check whether the cause of freezing was a one-off event or due to a structural defect that recurs every winter.

A stormwater system is one of the few systems in a house that collects dirt directly from the environment – sand, leaves, soil, and road grit. Without maintenance, every system will eventually become blocked.

• Empty sand and silt traps at least once a year, more frequently in high-traffic areas
• Clean gully gratings of leaves in autumn and spring
• Check gutters and downpipes after leaf fall
• In spring, check if water is collecting anywhere around the house
• Have the piping jet-washed if water starts draining slowly
• If in doubt, inspect the piping with a camera to find subsided or blocked sections

The largest portion of the cost is for excavation work and its complexity. Excavating a clear lawn area is quick; excavating under asphalt, block paving, or landscaping means additional demolition and restoration. Soil type also affects the volume of work – rocky or clay soil is slower.

Another factor is the length of the run and the number of chambers. Each chamber represents both material and labour costs, but saving on chambers is false economy: a piping system without inspection chambers cannot be properly cleaned later.

The third factor is the discharge solution. Connecting to the public network is usually cheaper than building a soakaway system, as a soakaway field requires a large excavation volume, aggregate, and geotextile.

We provide a quote after a site inspection, once the actual scope and solution are clear. This prevents situations where the quote and final bill differ significantly.

We perform both excavation and plumbing works, meaning the stormwater system is installed from start to finish by a single contractor – avoiding situations where the excavator blames the plumber, and the plumber blames the trench.

• Solution selection based on property and soil, not a template
• Excavation, piping, and chambers from one source
• Testing before backfilling the trench
• Video inspection option for checking existing systems
• Warranty for work performed and materials installed by us
• Service in Tallinn and Harjumaa, elsewhere in Estonia by arrangement