A FOUR-year-old boy has to drink more than 20 litres of water every day because of a rare kidney disorder.

Little Dominic Webster suffers from nephrogenic diabetes insipidus, which affects just one in 25,000 people.

The rare disorder means his body’s water regulating system is disrupted, causing him to suffer from extreme thirst.

Not only does Dominic drink gallons of water every day, he also has to stick to a low salt diet — and could need a kidney transplant when he is older.

His mum, Katie Webster, from Horwich, knew just after Dominic was born that something was wrong.

The 28-year-old said: “Dominic was under a paediatrician since birth and they checked for everything and said they would have to discharge him, but because I persisted they sent him for one last scan where they found he had problems.

“I felt relieved that they found something because I felt like I was being a worrying, hypochondriac mother but I also felt sad that he will be able to lead a normal but very limited life.”

According to NHS Choices, the condition affects one in 25,000 people, including adults, across the UK.

It is usually caused by injury or infection but people of all ages and ethnicities can be affected.

Medics do not yet know how Dominic’s condition will affect him as he grows up, but Mrs Webster, and her husband, Dominic’s dad, Neil, aged 44, have already been told that he has just 10 per cent function in his left kidney.

When he was a baby, Dominic suffered from unexplained fevers, vomiting, was irritable, had headaches and was constantly tired.

He was finally diagnosed with the rare condition in January.

Mrs Webster, of Evergreen Avenue, said: “He is very clever for is age and he is aware of his problems.

“He will say to people he has a kidney problem.”

She added: “We have to be very careful with his diet. He has to have a low salt and sugar diet and low protein diet with few processed meats.

“He drinks excessively — it can be up to 20 litres a day and will go to the toilet 20 to 30 times a day.

“When everybody at nursery is having cake and fruit drinks he can’t have them. He absolutely loves chocolate and sweets too.”

Mrs Webster said Dominic is able to eat most of the same meals as his brothers and sisters — Jordan, aged 11, Abigail, aged 10 and five-year-old Isabel, as she cooks his food in a different pan and does not use salt.

Dominic is not on any medication but has undergone several operations while under the care of three specialists at Royal Manchester Children’s Hospital, and he has appointments every six weeks.

To tie in with Dominic’s fourth birthday, which was on Tuesday, March 26, the family held a fundraising event in April on the playing field off Evergreen Avenue, to raise money for Kidney Research UK.