Even on a grey, rain-soaked day there are several people enjoying the beach at Brighton. 

Dedicated year-round swimmers come for a morning dip, a group of paddle boarders gather for a lesson, a man stands quietly fishing, while others walk their dogs. 

But no-one can be sure how clean the sea water here might be on any given day. The south coast of England has suffered more sewage spills directly into the sea than ever in recent months, a problem often exacerbated by heavy rain when outdated sewage systems are overwhelmed.

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The environmental campaign group, Surfers against Sewage, monitors spills and uses its Safer Seas app to alert sea users to potential sewage pollution. A series of red crosses indicate where the latest sewage leaks have been reported by water companies. 

"What we're seeing here along the Sussex coast is multiple events across multiple locations of raw sewage being emitted by the water companies," Stu Davies, the South of England Representative for Surfers against Sewage told CGTN Europe. 

"It's happening on a very regular basis. Right now, the entire switchboard of Eastbourne area is lit up red. That means all of those points, all of those combined sewage outlets are emitting raw sewage into that vicinity." 

The problem stems from outdated infrastructure, channeling sewage in antiquated pipes directly into the sea. "These were designed by the Victorians, it's Victorian technology. It's not fit for purpose for a modern coastal environment, or a modern city," says Davies.

Veronica Edmunds-Brown, Senior Research Fellow in Aquatic Ecology at the University of Hertfordshire, says that modern sewage waste, even when treated, can consist of a chemical cocktail of unknown substances, pharmaceutical products, heavy metals, acids, as well as microplastics which can be ingested by fish and passed up the food chain. 

"This is a public health issue as much as anything else, as well as an ecological issue," she says. "And it's a ticking time bomb. We really don't know what kind of issue this is going to have when things come through the food chain. Some of it will be ingested by organisms, usually within that coastal margin. Some will just sink into the sediments and will sit there and over time will break down. Others will sit there for very long periods of time."

Concerns over English sea water quality extend across the channel to France. French politicians say that the UK is not maintaining the same environmental standards after Brexit and are calling on the European Union (EU) to act to protect fish quality from pollution drifting across from UK waters.

The UK government has now set tougher targets for water companies, which pressures them to invest more in infrastructure, with a focus on protecting coastal areas. 

"This is the first government to take action to end the environmental damage caused by sewage spills. We will require water companies to protect everyone who uses our water for recreation and ensure storm overflows pose no threat to the environment," said former Environment Secretary George Eustice. 

"Water companies will need to invest to stop unacceptable sewage spills, so our rivers and coastlines can have greater protection than ever before." 

The plan involves billions of dollars of investment to increase the capacity to process sewage over the next 25 years, to tackle the problem by 2050. 

But campaigners say the government response is too little, too late. "We want to see an end to sewage pollution by 2030. We want to see a strong regulator, independent, and legislation that requires by law, the sewage companies, the water companies, to stop sewage pollution by 2030," says Davies.

But as the population continues to grow and waste water infrastructure comes under increasing pressure, the problem is likely to worsen in the short term.