Developers in Ireland and Northern Ireland are increasingly required to show how surface water will be managed as part of the planning process.

Planning conditions may ask for reduced runoff, controlled discharge rates, attenuation, water treatment, flood-risk reduction and a clear maintenance plan.

The most suitable Sustainable Drainage System, or SuDS, will depend on the site layout, ground conditions, available space and final discharge route.

What SuDS systems can developers use?

A development may use one or more of the following:

Rain Gardens and Rain Planters

Collect runoff from roofs, roads and paved areas, then temporarily store and filter the water through soil and planting before it is released.

View Rain Garden Solutions

SuDS Tree Pits

Combine stormwater management with urban tree planting, allowing runoff to support tree growth while also helping to reduce peak flows.

View Tree Pit Solution

Permeable Paving

Allows rainwater to pass through the paved surface into a drainage or storage layer below, where it can infiltrate or be released gradually.

Swales and Filter Strips

Use shallow planted channels and vegetated areas to slow surface water, remove sediment and guide runoff safely through the site.

Green & Blue Roofs

Retain rainfall at roof level, reducing the speed and volume of runoff entering the drainage system.

View Rain Garden Edging

Rainwater Harvesting Tanks and Water Butts

Collect roof water for reuse, such as irrigation, cleaning or other suitable non-potable uses.

Attenuation Tanks or Rainwater Storage Tanks

Hold surface water temporarily and release it at a controlled rate to reduce pressure on sewers and watercourses.

View Rainwater Attenuation Solutions

Soakaways and Infiltration Systems

Allow water to drain gradually into the ground where soil conditions, groundwater levels and site constraints make infiltration suitable.

Most developments benefit from a combination of systems rather than relying on one drainage product alone. This is often referred to as a SuDS management train.

What should developers check?

Before selecting a SuDS system, the design team should confirm:

• the wording of the planning condition;
• the permitted discharge rate;
• whether infiltration is suitable;
• the available storage volume;
• any water-treatment requirements;
• access for inspection and maintenance; and
• who will own and maintain the system.

In Northern Ireland, NI Water may influence the drainage strategy where a connection to the public sewer is required. In Ireland, the local authority will usually assess the surface-water proposals through the planning process.

A well-designed SuDS strategy can help developers:

• reduce pressure on drainage networks;
• meet surface-water planning conditions;
• control runoff rates;
• improve water quality;
• reduce flood risk;
• increase biodiversity; and
• create greener, more attractive developments.

Greenleaf Ireland SuDS solutions

Greenleaf Ireland provides integrated SuDS solutions for developments, streets, housing schemes, car parks and public-realm projects. Greenleaf Ireland can also support design teams with SuDS tree pits, rain gardens, SuDSPod systems, structural rooting systems and stormwater inlet solutions.

All SuDS systems should be designed for the specific site, hydraulic requirements, loading conditions and approval requirements.