Begin with the whole catchment area
The water reaching a car park may come from more than the parking surface itself. Adjacent roofs, slopes, access roads and neighbouring hardstanding can all contribute. Before choosing a drainage arrangement, the technical team should understand the area that drains towards the site and the intended destination of the collected water. Observe the existing routes during or after rain where it is safe to do so, and record problem locations with photographs. Those observations are useful evidence, but they do not replace the calculations or permissions that the project may require.
Coordinate the finished levels
Finished levels connect parking bays, pedestrian routes, building entrances and the public road. Changing one part can affect the others. A surface that drains away from one doorway may direct water towards another boundary if the wider levels have not been considered. The drawing should show enough information to understand these relationships and the position of collection points. Avoid treating drainage channels as an accessory to be added after paving. Their position and depth need to fit the planned layers, the available outlet and the way people and vehicles use the space.
Choose the system for its intended use
The appropriate arrangement depends on site conditions, the project design and the relevant local requirements. Surface channels, gullies, permeable systems and other solutions have different maintenance and ground requirements. A permeable finish is not automatically suitable just because water passes through its surface; the underlying layers and discharge strategy must also work. Likewise, a channel needs an appropriate connection and cannot solve a problem merely by collecting water in a new location. Ask the designer to explain the complete route from rainfall on the surface to the agreed final destination.
Look below the finished surface
The pavement structure needs to suit the ground and vehicle use as well as the chosen drainage approach. Weak or waterlogged layers can affect performance even when the upper surface appears well finished. Existing car parks may need investigation to establish why depressions or repeated potholes have developed. Repairs should address the cause rather than simply reproduce the damaged surface. When comparing quotations, identify excavation, sub-base preparation, drainage elements and paving separately. This makes it easier to understand whether a lower total reflects a different solution or leaves necessary preparation outside the scope.
Make maintenance possible
Drainage performance depends on keeping collection points and flow routes usable. Leaves, sediment and debris can obstruct inlets, especially near planted areas or unsealed ground. Inspection points should remain accessible after parking markings, landscape elements and other equipment are installed. The handover information should explain the relevant features and the maintenance tasks specified for the system. A practical layout makes those tasks easier. Consider how a maintenance vehicle or operator will reach the points needing attention without creating unnecessary disruption or having to remove unrelated parts of the finished car park.
Information to include in an enquiry
Send the location, approximate area, vehicle types and photographs showing the existing surface and surrounding levels. Explain where water currently collects and whether the problem occurs only in particular conditions. Include any available survey or drainage design and identify the intended use of the space. ECOSTA can then review the paving and associated civil works as a coordinated package. The key decision is not simply which surface looks best; it is how ground preparation, finished levels, water management and daily use will work together throughout the life of the area.
Test the maintenance scenario on paper
Before finalising the layout, imagine a blocked inlet after a period of leaf fall or nearby earthworks. Identify how someone would reach it, inspect it and remove the obstruction. This exercise may reveal a cover beneath a parked vehicle, an inaccessible outlet or a route that conflicts with daily use. Discuss the findings with the designer rather than making an unassessed change on site. Maintainability is a practical part of the drainage solution, not an optional addition after the paving is complete.