The Result
A plot type on a housing scheme exceeded the 110 litres per person per day target once the final bathroom package was confirmed. The client needed a quick fix — no redesign, no procurement disruption.
ATSPACE reviewed the water calculation, identified which fittings were pushing the result over the limit, and delivered simple specification changes that brought all affected plots back into compliance without affecting programme.
Project Snapshot
Service: Water efficiency calculations + compliance recovery
Client: Developer + principal contractor
Site: Stonebridge Mews, Plots 19–28, 1–10 Field Maple Close, Maidstone ME15 9ND
Development: New build houses (repeated plot‑type run)
Programme stage: Procurement finalisation + pre‑completion close‑out
Compliance driver: 110 litres per person per day requirement
ATSPACE delivery: Water calculator review, impact check, recovery options, updated calculations, evidence notes for procurement + Building Control
Team: ATSPACE compliance assessor + coordinator
Why the Plots Were Failing the Target
This plot type had several small specification pressures:
- two bathrooms including an ensuite
- large bath volume
- shower handset with a higher flow rate than assumed
- basin taps supplied with no flow restriction
Individually none were extreme, but combined they pushed the calculation above the 110 L limit.
Water compliance failures are usually death by small increments, not one obvious error.
What ATSPACE Was Asked To Do
- confirm how far above the target the plots were — and why
- propose simple, low‑cost, deliverable changes
- avoid redesign or bathroom layout changes
- provide updated calculation evidence quickly for procurement
- produce a defensible evidence pack for Building Control
What ATSPACE Did
Step 1: Isolate the drivers in the calculation
We analysed the calculation inputs to identify which fittings moved the number most.
On most plots, the biggest drivers are:
- shower flow rate
- WC flush volumes
- tap flow rates
Step 2: Provide simple specification‑change options
We recommended practical options that maintain look/feel and avoid redesign.
Typical measures:
- select a compliant lower‑flow shower handset
- confirm or add basin‑tap flow restriction
- confirm WC flush performance meets required values
- adjust bath volume only if necessary
Changes were minimal but high impact, easy to repeat, and procurement‑friendly.
Step 3: Recalculate + confirm compliance
Once options were agreed, we recalculated and confirmed the plots met the 110 L/p/d target.
Step 4: Provide procurement + evidence notes
We issued a concise note stating:
- what must be ordered
- what must be installed
- what must be evidenced
This protected compliance through to handover.
The Practical Changes That Made the Difference
The recovery required specification control, not redesign.
The most effective changes were:
- lower‑flow shower handset selection
- confirming tap flow restriction matched assumed performance
- verifying WC flush performance and recording it properly
Simple, targeted measures — not structural changes — delivered compliance.
Outcome
The plot type returned to compliance without redesign or programme disruption.
Project outcomes:
- water‑efficiency result brought below 110 L/person/day
- procurement remained on track
- repeatable compliant specification applied across the plot run
- updated, defensible evidence pack for Building Control
- reduced handover‑stage risk
Common Mistakes This Project Avoided
- changing multiple fittings without understanding the real driver
- redesigning bathrooms unnecessarily
- relying on generic tap/shower assumptions
- fixing only one plot instead of the whole run
- updating calculations without protecting as‑built evidence
CTA
If your water‑efficiency calculation exceeds 110 litres per person per day, ATSPACE can identify the true drivers and fix compliance with simple, practical specification changes — without disrupting programme.
Ask for:
- water‑efficiency calculation review + compliance recovery
- fittings‑schedule optimisation to achieve 110
- updated Building Control evidence packs
- support managing substitutions without losing compliance
Frequently Asked Questions
What usually pushes a plot over 110?
Shower flow rate, WC flush volumes and tap flow rates — especially on plots with multiple bathrooms.
Can we fix water compliance without redesign?
Often yes — targeted specification changes usually achieve compliance.
When should water calculations be checked?
As soon as bathroom/kitchen packages are selected. Leaving it late reduces options and increases risk.
