Tools & calculators
Eight tools for sizing tanks, choosing a pump, checking stormwater compliance, and pulling the drawings you need for consent.
How to choose
Start with what you are trying to size
If you know the product you need, the specification tools will get you to the right install detail and drawings. If you are still working out capacity or compliance, start with a calculator instead.
Some tools need a trade account
Tools marked Trade are available to Promax trade customers. A trade account is free and takes about a minute, and it also unlocks technical downloads across the site.
Rainwater and domestic water
Rainwater tank size calculator
Work out what capacity you need from your roof area, local rainfall and household demand.
Slimline specification tool
Pick the right tank, fittings and pump for tight sites, then grab the install detail, PS1 and plumbing schematic.
Pump selector tool
Answer a few questions on application, outlets, vertical lift and install location, and get a shortlist of pumps that suit the job.
Underground tank design
Underground specification tool
Match your site conditions to the right certified installation detail, covering soil, cover depth, traffic loading and risers.
Staged volume and orifice sizing tool
Find usable storage, partial fill volumes and invert levels for Enduro underground tanks, and size the orifice.
Stormwater compliance
SMAF calculator
Size detention and retention for Auckland SMAF areas so your design lines up with council expectations.
Stormwater detention PRE-POST calculator
TradeCompare pre-development and post-development flows, then size the detention storage needed to hold the difference back.
Wastewater and septic
Talk to our team.
Our team knows this range inside out. Tell us about your build, what you're trying to achieve, where it's going, or what you're unsure about and we'll come back with a clear recommendation. No jargon, no obligation.
- Personalised product recommendations for your specific project
- Spec, compliance and sizing guidance included
- Fast replies — usually within one business day