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Requirement H3 has three limbs. Adequate provision shall be made for rainwater to be carried from the roof of the building; paved areas around the building shall be so constructed as to be adequately drained; and rainwater from either shall discharge to a soakaway or other infiltration system, then a watercourse, then a sewer, in that order of priority and only where each earlier option is not reasonably practicable. In the Secretary of State's view those requirements are met where rainwater from roofs and paved areas is carried away from the surface, the system carries the flow to an outfall while minimising the risk of blockage or leakage and remaining accessible for clearing blockages, and water soaking into the ground is distributed so that it does not damage foundations.

Discharging to a watercourse is not automatically available. Approved Document H notes that discharge to a watercourse may require a consent from the Environment Agency, who may limit the rate of discharge, so a quotation that proposes running a new pipe to the nearest ditch should say who is obtaining that consent.

Mixing the two systems up causes trouble in the other direction as well. Surface water sent into a foul drain adds flow that the foul system was never sized for, and the right to connect to a public sewer under section 106 of the Water Industry Act 1991 comes with restrictions on what may be discharged where separate sewers exist. If a contractor proposes to connect a new soakaway overflow or a driveway channel into an existing drain, ask which system that drain is and on whose authority the connection is being made.

Approved Document H is specific about falls near a building. Surface gradients should direct water draining from a paved area away from buildings, and where the levels would otherwise cause water to concentrate along the wall of a building, a reverse gradient should be created for at least 500mm from the wall to divert the water away from it. Gradients on impervious surfaces should be designed to let water drain quickly, with a gradient of at least 1 in 60 recommended, while the gradient across a path should not exceed 1 in 40.

Draining to an adjacent pervious area is allowed, but with conditions that are easy to breach in a small garden. Paths, driveways and other narrow areas of paving should be freedraining to a pervious area such as grassland, provided the water is not discharged adjacent to buildings where it could damage foundations and the soakage capacity of the ground is not overloaded. Where water is drained onto adjacent ground, the edge of the paving should finish above or flush with the surrounding ground so the water can run off. Even pervious paving carries the same warning: a check should be made that stored water will not accumulate around the foundations of the building.

Planning rules reinforce the same point at the front of the house. The Planning Portal states that planning permission will be needed for laying traditional, impermeable driveways that do not provide for water to run to a permeable area where the surface to be covered is more than five square metres, and that permission is not needed where a new or replacement driveway of any size uses permeable or porous surfacing such as gravel, permeable concrete block paving or porous asphalt, or if the rainwater is directed to a lawn or border to drain naturally.

The regulations answer this in a fixed order, and a soakaway or other infiltration system comes first wherever it is reasonably practicable. Infiltration keeps rainfall on the site, does not load the public system in the storms when it is least able to cope, and avoids a connection that may need someone else's agreement. Where the ground drains and there is room to site a device clear of buildings, roads and the water table, it is normally the right answer.

Infiltration is not always possible, and Approved Document H says so directly. Heavy or already saturated ground, a high water table, unstable land, contamination risk, or simply nowhere that is 5m clear of a building or road all rule it out, and in those cases a watercourse, with any consent that requires, or a sewer connection becomes the practicable option. The honest version of that conversation includes a percolation test rather than an assertion about the soil.

LokalMatch is where the comparable quotations come from. Describe the problem once, saying where the water stands, what it comes off, what the ground is like and what you have already tried, and drainage contractors covering your postcode get in touch with you. They pay for the requests they receive, homeowners never do. LokalMatch does not design or build drainage, does not set prices, and does not vet, rank or recommend any firm, so asking each contractor how they established the soil's capacity and where the water will finally go is still your job.

Surface water and groundwater are not the same problem and are not solved by the same work. Approved Document C deals with the second: where the water table can rise to within 0.25m of the lowest floor of the building, or where surface water could enter or adversely affect the building, either the ground to be covered by the building should be drained by gravity or other effective means of safeguarding the building should be taken. Where there is a risk that groundwater beneath or around the building could adversely affect the stability and properties of the ground, consideration should be given to site drainage or other protection.

Two practical cautions come with that. If an active subsoil drain is cut during excavation and it passes under the building, Approved Document C expects it to be re-laid in pipes with sealed joints with access points outside the building, re-routed around the building, or re-run to another outfall — so a land drain found in a trench is not something to simply break and backfill. And general excavation work for foundations and services can itself alter groundwater flows through a site, which is why new drainage sometimes changes where water appears rather than removing it.

Before work starts, make sure the quotation says which problem it is solving. A scheme for roof and driveway runoff will not deal with a high water table, and a land drainage scheme will not stop a blocked gully overflowing at the back door. Ask for the two to be priced and explained separately where you appear to have both.