McNair Building Design — M&E Consultancy

Rainwater Systems

At McNair Building Design (MBD), we design rainwater systems that manage the collection and discharge of roof and surface water in a safe, reliable and compliant manner. These systems influence gutter sizing, downpipe routing, flow capacity, discharge points and the integration of architectural, structural and mechanical elements, making early coordination essential for successful project delivery.


Rainwater systems affect maintenance access, roof drainage strategy, equipment placement and compliance with environmental and building‑performance requirements. The overview below highlights the essential aspects of rainwater systems, and what they mean for the successful planning and delivery of your project.

Rainwater Collection

Rainwater collection systems capture water from roofs, terraces and external areas. They include gutters, outlets, hoppers and sumps designed to manage flow rates and prevent water ingress.

Typical PHE system elements:

Project impact

Rainwater collection influences roof layouts, outlet positioning, structural openings and the coordination of drainage with architectural and civil engineering elements. It affects maintenance access, waterproofing strategy and compliance with rainwater‑management requirements.

Rainwater Discharge

Rainwater discharge systems convey collected water through downpipes and drainage routes to attenuation, soakaways or below ground drainage networks. These systems require coordinated routing, pipe sizing and connection points.

Typical elements:

Project impact

Rainwater discharge influences pipe routing, riser planning, façade coordination and the integration of drainage with mechanical, electrical and architectural systems. It affects maintenance strategy, compliance with environmental requirements and long‑term operational reliability.

Integration with Building Services

Rainwater systems must integrate cleanly with mechanical, electrical, structural and architectural design.

Coordination requirements:

Effective coordination at this stage directly influences buildability, programme and longterm maintainability.

Construction, Testing and Handover

Rainwater systems require disciplined installation and testing to ensure performance and compliance.

Typical construction phase requirements:

A controlled testing and commissioning process ensures safe operation and longterm performance.

Early Engagement with MBD Makes a Difference

MBD provides coordinated, technically robust MEP consultancy across the full lifecycle of Public Health rainwater system design.

Early engagement supports clear decision making, coordinated layouts and efficient integration of rainwater systems with the wider building services strategy.

MBD provides coordinated, technically robust MEP consultancy across the full lifecycle of Rainwater Systems design:

Partner with MBD from Day One

Our approach ensures rainwater systems are safe, efficient and fully aligned with the wider building‑services engineering strategy.

To discuss how MBD can support your development, refurbishment or technical upgrade, get in touch today.

Contact Us

Make an enquiry

If you have a project that MBD can assist you with, please get in touch using contact form below.