A planning condition might require the preparation and approval of a surface water drainage scheme, before the approved development is begun, if that planning condition fairly and reasonably relates to the development permitted.
However a condition requiring the submitted scheme to achieve some improvement in the drainage of other land next to the site or nearby would offend the principle that planning conditions must fairly and reasonably relate to the development permitted. It might also be so unreasonable that no reasonable planning authority could have imposed it.
In the Court of Appeal case of Menston Action Group v City of Bradford Metropolitan District Council  the claimant challenged a planning permission.
Condition 15 of the permission said:
“15. Development shall not begin until a surface water drainage scheme for water passing through the site, based on sustainable drainage principles has been submitted to and approved in writing by the local planning authority. This must include details of how the surface water run off rate of 8.2 litres/second/ha will be maintained for up to and including the 1 in 100 year (plus climate change) rainfall event.
Reason: To prevent flooding by ensuring the satisfactory storage/disposal of surface water from the site.”
The claimant argued that condition 15 required the submission of a surface water drainage scheme in which “sustainable drainage principles” were properly represented. The claimant contended this would require it to be shown that the potential for reducing existing flooding, both on the development site itself and also in the surrounding area, had been considered. The claimant said a document submitted under condition 15 that failed to demonstrate that this had been done would not be capable of discharging the requirements of the condition.
Dismissing the claimant’s contentions the court said the condition “did not stipulate any improvement – or “betterment” – to the drainage of neighbouring land, or the alleviation of existing flooding beyond the boundaries of the development site.
…….The only measurable requirement in condition 15 is that the submitted surface water drainage scheme “must include details of how the surface water run off rate of 8.2 litres/seconds/ha will be maintained for up to and including the 1 in 100 year (plus climate change) rainfall event”. This specific requirement must clearly be in keeping with “sustainable drainage principles” in the sense in which that concept is used in the condition. And the reason given for the imposition of the condition – “[to] prevent flooding by ensuring the satisfactory storage/disposal of surface water from the site” – must also accord with those principles. The expression “[to] prevent flooding” here cannot extend to include the amelioration or elimination of existing flooding on neighbouring land. It can only mean “to prevent flooding arising from this development” – because it is, after all, the development itself to which the condition must fairly and reasonably relate. The means of preventing flooding is “by ensuring the satisfactory storage/disposal of surface water from the site” – that is, the site once developed.”
This blog has been posted out of general interest. It does not replace the need to get bespoke legal advice in individual cases.