The 70-year-old victim suffered a fractured cheekbone and bleeding to his brain after being punched and kicked by Adam Timmins during the disturbance.
Leeds Crown Court heard the incident took place a year after the victim first fell out with his neighbours when they began holding noisy late parties.
Paul Cleasby, prosecuting, said Timmins' sister and her partner are neighbours of the pensioner.
The prosecutor said the couple built a bar in their garden at their home on Lowfield Road, Dewsbury Moor, in the summer of 2020 and began hosting parties that "ran late into the night."
The victim had argued with his neighbours on a number of occasions about the parties being too noisy and going on too late.
The pensioner lost his temper on June 5 last year as his neighbours hosted another party.
Mr Cleasby said: "He went into his garden and turned on the hosepipe and aimed it over the fence."
The court heard two of the party goers looked over the fence and the pensioner squirted them with water.
The prosecutor said the pensioner was then told to come round to his neighbours' home.
Timmins, 35, punched him twice in the face and kicked him in the chest when he went to the property.
The victim returned to his home but was unable to sleep as he was in pain.
He went to hospital where it was found he had suffered a bleed to his brain and a fractured cheekbone.
Timmins, of Beckett Crescent, Dewsbury Moor, pleaded guilty to assault occasioning actual bodily harm.
The victim provided a statement to the court describing how he had suffered dizziness and loss of balance.
He has had to return his driving licence to the DVLA due to his injuries.
Mr Cleasby said he had also suffered flashbacks and had been afraid to leave his home since the incident.
Andrea Parnham, mitigating, said Timmins was sorry for what he had done.
The barrister said: "He accepts that had he been sober at the time he would not have reacted the way he did."
Ms Parnham said Timmins worked hard to support his children and would keep his full time job if he was not sent immediately to custody.
Timmins was given a 19-month prison sentence, suspended for two years.
He was also ordered to complete 15 rehabilitation activity requirement days and to pay £700 compensation to the victim.
Sentencing, Recorder Simon Myerson QC said: "I think you were so drunk you could not control yourself."