Where the money actually goes on a site
Two identical plots need one calculation, not two. That sounds obvious and it is routinely not how the work gets sold: most online services price the water calculation per dwelling, so a forty-plot site of one house type is forty purchases of the same arithmetic.
Our Part G water report is priced per dwelling type and covers every identical plot under it — see pricing for the full list. The same logic runs through the consultancy work: what multiplies is the plots that genuinely differ.
The full stack for a residential scheme
SAP at design stage and as built, the BREL report with plot-by-plot photographic evidence, an EPC per plot on completion, Part G water, Part O overheating, air tightness and sound testing — and an energy statement where planning asks for one.
Where a scheme sits in a nutrient-sensitive catchment there is a nutrient neutrality assessment too, and a calculator if you want to see the budget before you commit.
The two that catch sites out
Photographic evidence. It is plot specific. Every dwelling needs its own full set, geotagged and time-stamped, across six categories at stages through the build — and the assessor cannot sign the BREL declaration without them. Sites discover this at handover, which is the one moment it cannot be fixed.
Late specification changes. A design-stage SAP passes, then a heating system or a window spec changes on cost grounds, and nobody re-runs it. The as-built is where that surfaces, with the plots already built.
Common questions
Do we need a separate water calculation for every plot?
No. One calculation covers a dwelling type and every identical plot under it. You need a separate one per distinct fittings specification, and a plot schedule saying which plots each type covers — that schedule is one of the commonest reasons a submission comes back.
Can you work from a plot schedule and drawings alone?
Yes, that is the normal way in. Drawings, the plot schedule and the specification are enough to price the whole scheme and to run design-stage SAP. The site work — air tightness, sound testing, photographic evidence — gets programmed around your build.
How early should the design-stage SAP happen?
Before anything is ordered. Its entire value is telling you what the scheme is sensitive to while changing it is still free. Run late, it becomes an expensive record of a decision you can no longer reverse.
Not quite you?
- Architects & technologists — Settle the fabric at design stage, then hand us the compliance.
- Self-builders — What you can produce yourself, what you cannot, and when each is due.
- Assessors & consultants — The calculators, the working shown, and your name on the report.