It was a terrific battle between two hungry sides who gave it everything over the 90 minutes.
Castleview had it all to do as they were left with ten men on the pitch when goalkeeper Ryan McCarthy was shown a straight red after tripping up Damien McSweeney in the box around 40 minutes.
But, stand-in keeper James Nagle was superb and were it not for some super saves by him, the Loo could have won more convincingly.
Castleview started the brighter of the two and were in front on five minutes when after Ciaran Dennehy won good possession around the centre before setting off towards goal to rifle home the opener – despite Waterloo’s keeper getting a hand to it.
A quick response from Waterloo saw O’Donnell produce a decent run down the left channel before turning inside to force McCarthy to a low save at the near post.
But, from a free kick, a breaking ball bounces into the path of Brendan O’Donnell who shows a steadying touch before placing beyond McCarthy and restore parity once again on 13 minutes.
Castleview pressed soon afterwards with Evan Burke feeding Kelvin Greaney who hooked narrowly over with Alan Shine in close attendance.
And after a decent turn and strike by Evan Burke forces Keith Timothy to save, O’Donnell got away on the left before closing in to send a right-footed effort agonisingly past the far upright.
And after a speculative effort from Darragh Hurley was well held by McCarthy, Damien McSweeney finds Fionn Hall with his cross, but the defender lacked force on his header as the View’s keeper picked with ease.
Brendan O’Donnell then threatened again when he was denied by another decent save by the View’s keeper.
A great run then from Castleview’s Daniel O’Donoghue ended with the striker being denied by a decent save by Timothy from his crisp effort.
O’Donnell was looking dangerous on the ball now for Waterloo and once again he threatened, but steered wide of the post with a low effort.
Castleview were confronted with an uphill struggle after that when their goalkeeper was sent from the field of play for a foul inside the box on McSweeney which resulted in outfield player James Nagle going between the posts for the rest of the game.
Brendan O’Donnell was entrusted to take the penalty shot, but was denied by a superb save from stand-in keeper Nagle.
And just before the break, O’Donnell was once again denied by yet another superb block from Nagle as the half-time whistle brought a super first 45 minutes to a close.
With just minutes into the action of the second period, View’s stand-in keeper was called upon once again – this time to produce a fine save from Danny Whittington at the expense of a corner.
Up against the numerical disadvantage, Castleview were cautious in their approach and had plenty behind the ball as they looked for an opportunity to break, but were relieved when Shane O’Leary just fails to get a nick on Finbarr O’Shaughnessy free kick while unattended near the far post.
The decisive moment arrived in the 65th minute when Eoin O’Connell’s cross reached the available Brendan O’Donnell whose powerful effort with his head reached the Castleview net – despite Nagle getting a touch to it.
Despite, a gallant effort from Castleview to chase an equaliser, Waterloo held on well in the end.
Waterloo: Keith Timothy, Martin McGreevy, Alan Shine, Darragh Hurley, Fionn Hall, John Hegarty, Finbarr O’Shaughnessy, Damien McSweeney, Danny Whittington, Brendan O’Donnell and Frank McCarthy.
Subs: Shane O’Leary and Ian O’Dwyer for John Hegarty and Martin McGreevy (57), Anthony Cahill and Scott Shine for Alan Shine and Danny Whittington (65), Damien Ronan for Damien McSweeney (83).
Castleview: Ryan McCarthy, Dylan McCarthy, Dylan Cambridge, Dalian Wall, Derek Kiely, James Nagle, Kelvin Greaney, Thomas Fitzgerald, Evan Burke, Daniel O’Donoghue and Ciaran Dennehy.
Subs: Sean O’Mahony for Dylan Cambridge (half-time), Gavin Duggan for Ciaran Dennehy (57), John Compardi for Kelvin Greaney (65), Michael Kiely for Evan Burke (68), Eoin O’Connell for Dylan McCarthy (86).
Referee: Brendan O’Regan.