A London bus driver has launched a campaign over the shortage of toilet facilities on some routes, saying colleagues are left with no option but to urinate in bottles.

Muhsin Manir has driven buses in south and east London for 18 years. He says that on routes without facilities, drivers are left choosing between paying out of their own pocket at a cafe or restaurant, or simply going without — a particular problem on early morning and late night shifts, when little is open. During heatwaves, when drivers need to drink more, he says the situation becomes especially difficult.

"Sometimes we have to use a bottle, or you have to go to the park," Manir said. "It's unacceptable — there's nowhere to wash your hands as well."

His campaign has started with routes 115 and 58 near East Ham Central Park, and has gathered more than 300 signatures so far. But the problem he is describing is not confined to those two routes. Figures from the GMB Union suggest at least 175 London bus routes have no dedicated driver toilet at one terminus.

Manir believes the gap comes down to spending decisions rather than practicality. "They don't want to spend the money, and it's a political choice," he said.

Transport for London said it has installed or refurbished 154 toilet locations over the past eight years, and that "the vast majority of routes have suitable toilet facilities at their termini".