MPs who voted against putting a legal duty on water firms to stop pouring raw sewage into rivers and seas could yet be forced to debate the issue again.

Last week's controversial decision has sparked anger from campaigners - but ministers have defended the move. Here's everything you need to know...

Why is sewage dumped in the sea?

Sewage can be pumped out of the sewage system and into rivers and seas through combined sewer overflows - otherwise known as a storm overflow or release valve.

The overflows are designed to release excess water following heavy rainfall or a storm, to stop sewage backing up into homes and buildings.

What is the problem?

The Environment Agency says that in the last year, raw sewage was discharged into coastal waters and rivers in England more than 400,000 times, which Defra (the Department for Environment, Food and Rural Affairs) branded “unacceptable”.

Critics are concerned waste is being dumped too frequently into our oceans, and that water firms such as Southern Water - which provides water and waste water services for Kent, Sussex, Hampshire and the Isle of Wight - are using it as a cost-saving measure.

They argue that water companies hide behind heavy rainfall excuse as a way to frequently discharge huge amounts of waste.

Frequent sewage discharges have taken place around the Kent coast, in areas controlled by Southern Water.

The water firm was slapped with a record £90 million fine in July after unleashing up to 21 billion litres of sewage into protected water between 2010 and 2015.

But the issue has persisted, and recent sewage discharges incidents have led to frequent public warnings, with people urged not to enter coastal waters in popular spots such as Whitstable, Herne Bay and Thanet, over health and safety concerns.

Hundreds of people have attended marches in places such as Whitstable and Margate in recent weeks, calling for the practice to be stopped.

They argue it is damaging the reputation of popular seaside towns, and causing those who swim in the sea to fall ill.

What is happening with the Environment Bill?

A new Environment Bill is currently being debated by lawmakers.

It aims to change the law to reduce sewage entering our rivers and seas from storm overflows - by placing a range of new legal responsibilities on water companies to tackle water pollution.

The House of Lords passed a three-and-a-half page amendment to the Bill - the Duke of Wellington's Amendment 45 - which would see stricter action taken against water firms that dump sewage into the country's waters.

It would see a plan put in place to reduce the number, and length of sewage discharges.

It would also mean the Environment Agency and water firms would have to publish annual reports providing details about their storm overflows.

The House of Lords passed the Bill.

But when it came before the House of Commons last week, the Conservative government whipped Tories into removing seven key lines of the amendment.

Those seven lines would have meant water firms had to legally "take all reasonable steps to ensure untreated sewage is not discharged from storm overflows”.

Such a move would have left the government having to take action against those that fail to do this.

Some 202 MPs voted against stripping the seven lines from the amendment.

This included 22 Tory MPs - including four from Kent - who opted to go against the government.

One of the Tory rebels was South Thanet MP Craig Mackinlay, whose constituency falls in the district worst impacted by continual sewage discharges.

Tory MPs Tracey Crouch, Kelly Tolhurst, Greg Clark and Gordon Henderson also voted against stripping the lines from the amendment, as did Labour MP for Canterbury Rosie Duffield.

But the amendment was ultimately passed with the seven key lines removed, after MPs voted by 268 to 204.

Why are people angry?

The vote has sparked fury from campaigners.

A social media campaign has seen hundreds of people take to Twitter to shame MPs who voted against the amendment, sharing their names and photographs and claiming they "voted to allow raw sewage to be dumped in our rivers".

Campaigners say they are “disappointed” that MPs failed to back the campaign to put a legal duty on water companies to stop raw sewage from being poured into waterways.

They are pressing for water companies to pay to restore England’s coastlines after dumping sewage into rivers.

Hugo Tagholm, the CEO of Surfers Against Sewage, who appeared at a march against Southern Water in Whitstable earlier this month, says water companies have not “got a right to destroy these spaces”.

He told BBC Breakfast on Tuesday: “The amendment that is being called for is reasonable. We believe the water companies need to cut into dividends they make every year to restore our rivers and our coastlines.

“They haven’t got a right to destroy these spaces and need to take the ambitious steps to restore them and we need to make sure the industry is not putting their profits ahead of making our spaces safe.”

Surfers Against Sewage said in a blog post last week that it will continue to rally, with Mr Tagholm saying: “In this most important of environmental decades, it’s shocking that the Government recommended that MPs reject progressive and ambitious amendments that would protect water, air and nature.

“Why wouldn’t they want water companies to have a legal obligation not to pollute our rivers and ocean with sewage? It beggars belief and hardly shows a commitment to be the greenest Government ever. It’s time for more ambitious thinking and law that builds protected nature back into public ownership rather than leaving it to the ravages of shareholder interests.”

What does the government say?

MPs who voted for the seven lines to be removed have hit back at the widespread claims they "voted to allow" the dumping of sewage.

They say astronomical financial repercussions of reforming the nation's waste water system is one of the key reasons behind the move.

MP Rebecca Pow, Parliamentary Under Secretary of State at Defra, said it would cost approximately "between £150 billion and £660 billion" to update the country's Victorian sewage system and "eliminate storm sewage overflows".

She said in Parliament: "One must consider the cost of bills, because there will be an impact on those.

"We will soon have the data from our storm overflows taskforce, and from our duty to report on what the cost benefits would be of completely eliminating storm overflows.

"Such things are used far too frequently, but they are also an emergency measure that should potentially always remain, just in case we have to deal with huge floods."

Defra has also penned a lengthy post in defence of its actions.

It says work to prevent sewage being dumped in the sea would include the complete separation of the sewerage systems which could lead to “potentially significant disruption for homes, businesses and infrastructure across the country”.

However, they have “made it clear to water companies that they must significantly reduce sewage discharges from storm overflows as a priority”.

What do Kent MPs say?

MP Rosie Duffield, whose constituency town Whitstable has been blighted by Southern Water's sewage discharges, has slammed the changes to the amendment.

She said: "The government removed the crucial lines from that particular amendment that had any 'teeth' to impose meaningful sanctions on those polluting water companies.

"The incidents are now no longer rare occurrences but regular events.

"Every time we experience heavy rain in Whitstable, or a storm, we know that we will be unable to enjoy the beach for swimming, sport, leisure activities, or pleasant dog walks around Swalecliffe.

"We cannot open our windows, hang out our washing and children are breathing in potentially extremely unhealthy particles.

"This has got to stop. It is damaging our daily way of life here and will have a knock-on effect on the local economy as tourists reconsider visiting out beautiful coastal town."

Conservative MP for North Thanet, Sir Roger Gale, was unable to vote due to his involvement in the Bill's process through the House.

But the veteran Tory has taken to Twitter to make his stance clear.

He said: "I, like many of my constituents, am appalled to see the way in which Southern Water keep using our bathing waters as a dumping site.

"As chair, I am obliged by parliamentary rule to take a neutral position in the voting lobby.

"However, I have voiced my concerns to the government, I have also written to Southern Water and the Environment Agency as we must stop the dumping of sewage in our waters.

"For the health and safety of my constituents and for the protection of our environment and coastline. It’s time that Southern Water take responsibility for their actions."

Craig Mackinlay, the South Thanet MP who defied the Tory whip to vote against the removal of the seven lines of the amendment, said the dumping sewage into the sea "cannot continue like this".

He said: “I have long been extremely concerned by the problem of sewage polluting our beaches; not least by the latest failure of the pumps at Southern Water’s Broadstairs Wastewater Pumping Station on the morning of October 5 causing the closure of all Thanet beaches once more.

"Such instances occur with alarming regularity and are causing anger and resentment among our residents.

“Despite the £90m fine levied against Southern Water in July and subsequent new ownership, I need to be completely reassured as to their commitment to prevent such discharges. We need to ensure that water companies take more seriously the need to reduce raw sewage discharges into rivers and coastal areas.

"That is why I voted for the Duke of Wellington’s well-intentioned amendment.

“Ministers sought to reassure me both before and after the vote that this amendment is already delivered through the many measures within the Environment Bill and more broadly. I very much hope the Government keeps its promise to us here in Thanet and will be urging them in no uncertain terms to do so. We cannot continue like this.”

The Environment Bill is due to go back before the House of Lords for scrutiny today.

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