Save Windermere campaigner Matt Staniek has begun a weekly protest outside United Utilities' Windermere Information Centre.
Matt Staniek told ITV Border, "This is my version of a peaceful protest, very much inspired by Greta Thunberg and what she did for the climate strike for a future."
Water UK says water companies are nearly doubling their investment in sewage infrastructure with £96billion set to be invested in over 100,000km of sewer network between 2025 and 2030, but the local campaigner says that's not enough.
United Utilities says customers are consulted at the shop of Windermere's high street, shaping their plans.
It says in the last three years it's invested more than £75million in wastewater infrastructure - with a further £41m up to 2030, halving phosphorous levels in Windermere.
Mr Staniek says: "We're saying Windermere is the most significant lake in this country. It symbolises freshwater in this country and why we are we putting sewage into it? You know, last year alone, United Utilities sent £300 million to their shareholders in dividends.
"And they weren't investing in the problem. And the problem is, is that putting sewage into the lake. So we're saying, well, instead of spending money on an information centre and what we would see as a means to show the public that they're looking everywhere else but themselves, we're saying that money should be invested in the infrastructure."
The campaigner hopes to be joined by others in the coming weeks but for now he says he'll be there every week until sewage is no longer going into England's longest lake, Windermere.
When asked if one striker could make a difference, Mr Staniek says: "It's not necessarily just going to be me. People are wanting to join.
"This is about a sense of community. We don't have to put up with this. We don't have to just accept that sewage is going into Windermere. We can actively do something about it, you know? It all has to start with one person. You know, this may be one person now, but it doesn't have to be."
A sign on United Utilities window in its customer information centre says Windermere has "excellent bathing quality status."
Mr Staniek says that's misleading, he said: "The Environment Agency samples 20 times in 153 days of the bathing water season. They sample for two bacterium: intestinal enterococcus and E.coli.
"They don't actively sample for things like blue green algae. Last summer, the entire north basin of Windermere turned bright green on the 13 of August.
"At that moment in time, because of the concentration of citrobacter present that posed a direct risk to your health if you were to swim not only from skin irritation, but if you were to accidentally ingest that water. There were no signs warning people not to be entering the lake. So the idea of Windermere's bathing water sites being classified as excellent is not a true representation."
Water UK says nationally customers' bills will rise by £13 a month on average by 2030 to pay for investments in wastewater infrastructure.
United Utilities calls its investment "part of a record £13.7 billion programme across the North West".
Matt Staniek says a water company that paid its shareholders £300m last year should be footing the bill, and he'll be staging his protest every Monday until they do.
A United Utilities spokesperson, said: “Our Windermere information centre has been open for three months and it’s been great to meet with so many of our customers and visitors to the area. We’ve welcomed many visitors through the door to help with their queries on everything from water meters and bills to our recent and forthcoming investment around Windermere and wider Cumbria.
“Since 2000 we have invested more than £75m improving our wastewater services around Windermere which has halved the levels of phosphorus entering the lake. We have plans to invest a further £41m up to 2030, part of a record £13.7 billion programme across the North West. These plans have been shaped after consulting with our customers to tackle the issues that matter most to them right across the region we serve.
“We will also be holding drop in events later this month so that people can find out more about the specific improvement work we have planned for Windermere over the next two years. These are between 2pm-7pm on Monday 20 November at Hawkshead Market Hall, Hawkshead; Tuesday 21 November at the Marchesi Centre, Windermere; and Wednesday 22 November, Ambleside Parish Centre, Ambleside.”
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To know...