One in five local education authorities still has primary schools with outside toilets, according to the Campaign for State Education. Twelve out of the 57 LEAs which replied to a CASE survey had one or more primary schools with only outside lavatories.
Derbyshire, Devon, Gloucestershire, Somerset and Dyfed all had a dozen or more primary schools without inside toilets.
CASE carried out the survey to focus on the need to spend more on school buildings, and will be publicising this issue in its Classroom Charter campaign this year.
Margaret Tulloch, CASE's executive secretary, said: "It is ironic, when all parties are emphasising the importance of linking schools into the information superhighway, that because of persistent low spending on buildings some primary children still face a freezing walk to an outside lavatory!"
The Classroom Charter calls for minimum entitlements for all pupils, wherever they go to school: "genuine" nursery provision; primary classes with fewer than 30 pupils; safe and up-to-date buildings; funds for enough books and equipment; all pupils' special needs to be met; and fully-qualified teachers.
CASE says it blames the Government for successive years of inadequate funding for school buildings.