Schools have to follow lots of rules when they design new toilets. Accommodating transgender students isn't one of them.

Secondary teacher union the PPTA has released new guidelines, advising schools to provide gender-neutral uniforms, toilets and changing facilities.

Newstalk ZB has obtained a letter the Ministry of Education sent to the mother of a transgender student earlier this month.

The ministry said school boards have complete discretion to manage schools as they see fit, and interpret relevant human rights laws.

It said boards will make decisions based on their school's character, culture, philosophy, community and student body.

The ministry has produced 21 pages of guidelines of school toilet design, which prohibit slab urinals, non-porcelain bowls and cold water taps.

Those guidelines advise schools to factor in gender balance, school age, and undefined "cultural considerations".

Schools can access a suggested unisex toilet design, but the guidelines don't make suggestion for schools to consider the needs of transgender students.

Some of the Ministry's guidelines for designing toilets

- Toilet pans must be vitreous china, floor mounted and back-to-wall.

- Toilets must be fully self-contained with a basin and hand-drying facilities within each cubicle. Basins in the lobby are optional.

- Basins should have warm water, but not water above 45 degrees, with a single tap and a sink plughole.

- School toilets shouldn't be available outside school hours and specific purposes.

- Toilets should be in small groups, with glazed doors, sidelights, windows, and indoor and outdoor access for "passive supervision".

- A school needs to make sure it has enough male-only and female-only cubicles before installing urinals.

- Slab urinals shouldn't be installed, and should be removed from any remodelled toilets.

- Toilets should be designed with good ventilation, and the toilets should be able to ventilate securely and safely outside school hours.

- Toilet, plumbing components, and electric hand dryers should never be located in a wall shared with a teaching or office space.

- Self-contained toilets must have "aural privacy" and some degree of cubicle privacy.

- Toilet walls should be graffiti-resistant, and toilet ceilings shouldn't be too high for students to access.

- Flush systems should be time-flow controlled and lights should be LED and controlled by an occupancy sensor.

- Toilets should only have very specific floor and wall finishes, which absorb sound and are easy to clean.

- Cisterns must be duel-flush, and concealed in wall cavity with vandal-resistant access panel and fixings.

- Mirrors must be clear of the basin, and soap dispensers must be next to the basin but not fixed to the mirror.