Sewage has spillt out of drains and onto streets after heavy rainfall caused flash flooding across the country.
The Scottish Environment Protection Agency (SEPA) issued flood alerts on Tuesday and Wednesday
The watchdog warned wetter conditions were expected and urged the public to be prepared.
Scottish Water said the adverse weather was “affecting sewer related issues”.
Flash flooding affected Edinburgh, Glasgow, Uddingston, Coatbridge, Paisley, Ayr, Kilmarnock, Paisley, Galashiels, Penicuik, and Musselburgh.
A resident in Perth and Kinross said raw sewage was flowing out of an access cover and running down driveways.
A spokesperson for SEPA said: “Wet weather conditions over the last few days have led to some localised flooding impacts across Scotland. Heavy, slow moving showers have the potential to cause localised significant flooding impacts, especially where the heaviest of the showers impact infrastructure (road or rail) and urban areas where drainage systems and urban watercourses could quickly become overwhelmed, resulting in rapid flooding.
“Combined Sewer Outfalls (CSOs) are an integral part of Scotland’s sewerage system, designed to discharge at times of high rainfall to prevent sewage backing-up and flooding houses, and SEPA regulates discharges to the water environment, including discharges from CSOs.
“SEPA is working closely with the Scottish Government, local authorities, Scottish Water, environment and community groups and others, regulating activities where required as together we take the next steps to deliver an even better water environment for our nation as part of the River Basin Management Plan published in December 2021.
“This includes taking a radical new approach to managing rainfall which uses blue-green infrastructure to absorb rainfall, reduce flood risk and minimise sewer overflow spills.”
A Scottish Water spokesperson said: “Heavy rainfall across parts of Scotland in recent days caused some localised flooding and, in some cases, led to sewer systems being overwhelmed.
“We responded to any reports of sewer flooding as quickly as possible and clean-ups were carried out where necessary.
“Anyone aware of sewer flooding should report it directly to us on 0800 0778 778 and we will respond as quickly as possible to investigate.
“We take our environmental responsibilities very seriously and are committed to transforming our waste water network across Scotland to help protect its water environments. We have invested significantly in our treatment works, sewer upgrades and have committed to further activity which will see more investment to improve water quality in line with national targets.
“Customers can also help us by disposing of items such as wet wipes properly, and not flushing them down toilets where they cause blockages, flooding and pollution in our rivers.”