It's a mess that affected her business and customers, and Tutira's Jill Dornan wants to know exactly what fell on her shop - and where it came from.

After serving a customer at 8.45am yesterday, Ms Dornan and the customer found a car and the building covered in what she says is human waste.

It had also fallen on the roof of the Tutira Store, splattering the sides of the building and the nearby information sign.

"I've been shat on and no one gives a s***," Ms Dornan said.

"Everyone's trying to figure it out but no one's taking responsibility."

Ms Dornan had contacted Hawke's Bay Airport and the Civil Aviation Authority to find out about flights at that time and was told there were no airplanes overhead then.

Because of the pattern it fell in, Ms Dornan said it was dropped from the air by something travelling north.

It contained pulpy bits of paper, some with a pattern of lines or writing visible on it.

Tutira School secretary Judy McKinnon's car ended up covered in the substance, which she said did not smell and seemed like mushed newsprint.

An Air New Zealand spokesperson said the Tutira Store was not under any flight paths so the substance could not have come from one of its aircraft.

Following incidents where a substance hit houses in South Auckland, Civil Aviation Authority spokesperson Emma Peel said it was not possible for planes to release human waste in the air.

The CAA told Ms Dornan it was probably from a big flock of birds flying overhead that were scared, possibly by a hawk.

"I said not unless the ducks are using toilet paper. He told me I'd have to prove it was toilet paper."

She had taken samples which would go to a lab in Napier for analysis.

"I just want to know what it is and where it came from. Someone's got to tell me something."