Scottish Water say engineers have been working round the clock in a bid to stem the flow of millions of litres of sewage into the Firth of Forth.
People using the waterfront have been urged to take precautions
The major spill was caused by a pump failure at Seafield Wastewater Treatment Plant in Leith on Friday.
It is hoped a new pump can be fitted to stop the overflow by the end of Sunday.
The public has been warned to avoid contact with water as 1,000 litres a second of partially diluted sewage pumps into the Forth.
The plant, run by Thames Water, treats sewage for 800,000 people in and around Edinburgh.
The Scottish Environment Protection Agency said emergency measures to "minimize the risk of pollution" were being put in place and warned the public not to come into contact with the water.
Peter Farrer, general manager for Scottish Water, said: "There has been a catastrophic failure of one of the large pumps at Seafield which pumps waste water into the treatment works.
"We have had teams of engineers working around the clock to try and rectify this problem.
"The pumps are on their way and when the pumps are put into place then that will rectify the problem."
Mr Farrer said the failure affected just one of the flows going into the treatment works and that Seafield continued to treat the rest of its intake as normal.
He said it was impossible to stop the flow as the system is designed to use the emergency overflow into the Forth when something goes wrong.
A pump has to be replaced so the plant can resume full operations
Mr Farrer insisted that because the effluent was flowing through a screening process, which takes out solid material, "aesthetically you won't see anything from the discharge".
John Rae, the General Manager of Customer Operations for Scottish Water, explained that the sewage flow would have to be diverted before higher capacity pumps could be installed.
"The line that's coming in where we have the problem is only about a quarter of the total flow that Thames actually treat. Now in saying that, it's still a huge flow that's actually coming in - so they have to be able to divert that fully to stop the emergency overflow from running."
Scottish Water also apologised for any inconvenience to its customers.
Gordon Greenhill, head of community safety at Edinburgh City Council, said the sewage spill raised public health concerns but would not be a long-term environmental problem.
"The volume of sewage going into the Forth estuary is a concern as it has the capacity to come back on to the shore," he said.
"Any raw sewage has human pathogens in it which has the capacity to make people ill."
Residents in Leith have been campaigning for years about the smell from the plant and say it is not fit for purpose.
Rob Kirkwood, the chairman of Leith Links Residents' Association, said: "It has an infrastructure that is basically Third World technology."
Do you live near the Firth of Forth and have you been affected by the spill? Have you been on the waterfront and can you see the effects of the leak?
Please send us your comments and experiences using the form below.
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There is no excuse for having no contingency plan in place for such an event as this. The scale of the pollution defies belief. Heads must roll.
Daniel Evans, Edinburgh, Scotland
I live on the Shore area of Leith and fortunately we do not get too much of a smell due to the prevailing wind. I pity the poor souls who live opposite this plant as it must make their eyes water. It really is time that the great and good of Edinburgh did something to improve the environs of this route into the city.
John Pendlebury, Leith, Edinburgh
I took my two children (two and four years) to Portobello beach on Saturday morning. This is next to the Seafield site. There were no signs or anything. We all had waders on and went paddling in the low tide. We caught a crab and several rag worms which we all handled and then put back. There wasn't anyone else on the beach except dog walkers but that was normal for the weather. Nobody said anything to us and as usual we chatted to several people. We are all in good health today but thanks Thames Water. Why don't you make it really difficult maybe impossible to pump sewage into the sea.
Andy Law, Edinburgh
: I spend 3 hours dinghy sailing on / in the Forth yesterday. It was a windy day and my fellow sailors and I were fully immersed in spray. I await the onset of GI symptoms with trepidation! Mistakes shouldn't, but do happen. However, the 40 hour delay in alerting the public is unforgivable. This incident happened during business hours on Friday afternoon. Failure to give immediate notice is nothing short of criminal corporate negligence.
Robbie Lawson, Edinburgh
This morning I have been in contact with SEPA, and Edinburgh Council's Environmental Health Dept with regard to lack of information and what, if any impact this will have on those of us that were sailing and getting very wet yesterday, as the general advice is to avoid contact with the water. The Edinburgh EHO was concerned that the information hasn't reached the people it needed to, but said that any ill health would be unlikely due to the dilution effect of the Forth. He did say that they would be monitoring it and that they would be looking at how to better communicate these incidents to groups like ourselves in the future. Not satisfactory but better than SEPA's response which was that it really wasn't their concern how it effected beaches and people, but how the leak happened. Not good for an Environmental Agency.
I will be trying to contact East Lothian to find out why they didn't notify anyone including harbourmasters, as all warning signage stops at the end of Portobello prom at Joppa.
Chris Tierney, Joppa, Edinburgh
We went for a walk along Crammond on Saturday afternoon, when we got there we could smell the problem. There were no notices indeed it was only as we returned from our walk we were stopped by someone and informed of the incident verbally.
Duncan Wallace, Edinburgh
Next it will be a major spill from the proposed oil transfer on the Forth. Mix this in with all the other industrial chemicals and waste and the Forth can be declared dead. The bottom line is that our government and the industry treat the Forth like a giant cesspool and see it as an asset for profit and not for its critical importance as part of the local ecosystem or for its beauty.
Tony, Culross, Fife
There were no warnings that I saw posted anywhere near Portobello Beach (just a mile or so down river) this morning when i was there briefly with my 2 children. Frankly this is just another one in a series of problems we have had with this plant - there have been constant complaints and even demonstrations regarding the smell from this plant. Thames water have promised to solve the problem but its been going on for years.
Rodger Moffet, Leith, Edinburgh, Scotland
I live beside the Firth of Forth and work beside Seafield sewage plant. The plant is a disgrace & has been the subject of many complaints for years. The surrounding area stinks, blamed as usual on old equipment. The council has repeatedly ignored calls for the plant to be updated and this major spillage comes as no surprise to many locals who have known for some time that it is substandard & should have been closed years ago.
Simon Arbuthnot, Edinburgh, Scotland
I was surfing at Pease Bay on Friday unaware until Sunday morning that this has happened. I want to know if we have been contaminated. This is disgusting and not good for the environment.
Grant Finlayson, Edinburgh
Here in west Fife there are signs of this filth being washed up already. Walking the dog this morning (before I heard the news), I remarked to my wife how filthy the beach looked. There are examples of human waste in several places. We are having reasonably high tides at the moment (the new moon has just passed) and I hope that this afternoon's high tide will clean up the landscape. My fear is that, as we're moving towards a week of lower tides, some of this filth gets left on our waterfront. I hope that Hilary Bennet and Edinburgh City Council remember that we're being affected by this here in Fife and do something about it.
Eric Blair, Rosyth
We live on the shore of the Firth of Forth in Portobello and along the prom the notices that have been put up are very few and far between and pathetic - considering this is quite a serious problem. There should surely be some major signs up, not just some A4 pieces of paper tied with string ???
Steve Lavender, Portobello, Edinburgh