The parents of two-year-old Aisling Symes, who drowned in a west Auckland stormwater drain after falling through a faulty manhole cover, hugged and exclaimed "it's over" after coroner Garry Evans today completed the inquest into her death.

Angela and Alan Symes had been visibly upset at times throughout the three days of the Auckland inquest into the death of the toddler, whose body was found in a stormwater drain in suburban Henderson on October 12 2009, eight days after she disappeared.

Mr Evans will announce his finding later.

This morning the inquest heard that the stormwater pipe where Aisling died was supposed to have been replaced two to three years before the tragedy.

The pipe was decades old and never designed to service infill housing.

Evidence showed it was likely that water pressure popped the manhole cover off while Aisling's mother, Angela Symes, was cleaning out the home of her late parents.

Seven days later, Aisling's body was found 36m down the stormwater pipe.

The former Waitakere City Council had received numerous complaints about the drain.

Council field services manager Stephen Challis went out and visited the site one month before Aisling's death.

He ordered a flushing but confirmed to coroner Garry Evans that the flush was only a short-term solution.

He said the drain was supposed to be replaced in the 2006-2007 financial year but that work never went ahead.

He suggested that all 42,000 manholes in the Waitakere area should be fitted with a $480 fitted safety grate.

The total cost would be in the vicinity of $20 million.

Auckland Council environment infrastructure manager John Dragicevich said the cost for the entire Auckland area would be about $70m.

He said the council has already identified 283 manholes which are susceptible to dislodging in a heavy rain event and will fit all of them with a safety grate by July.

"The council is committed to ensuring that manholes do not pose an undue risk to the public access the Auckland region so that further tragedies do not occur."

Council water services manager Richard Taylor yesterday said the pipe where Aisling was found was built in the 1970s and was designed only to drain the roads.

Mr Taylor said the drain network that Aisling fell into was on a low priority for replacing.

"We didn't appreciate the risk of a toddler falling into a manhole, so it was off the radar."

Housing New Zealand asset manager Sandra Bond said she called the council in 2008 and told staff the manhole cover was lifting. She phoned them again a year later because the problem had not been fixed.

"I did believe there was a risk of a child standing on the manhole cover.

"I said: 'Every time the manhole cover pops off, we potentially have a situation there because we have young children there and the manhole cover is easily accessible on the driveway'."

Coroner Garry Evans asked Ms Bond what Housing NZ did when it received complaints about the manhole cover popping.

She replied that the stormwater drain belonged to the council. "Beyond ringing the council - nothing, to my knowledge."

In 2009 - a month before Aisling died - the council sent out a contractor to run a CCTV camera along the drain.

William Ihimaera managed the job for council contractor BBS.

He said they found tree roots blocking the pipe and decided to flush the line.

Coroner Evans asked Mr Ihimaera if he was aware at the time that, with further rain, the manhole lid would continue to pop out.

"Did you ask yourself, 'In the meanwhile, should we put in a grill or net?'"

Mr Ihimaera said he did not ask himself that question.

He said nowadays a 200-litre drum full of water is placed over a manhole until a steel grid can be fitted.

His boss Robert Coe said his company relied on the council engineers to direct what work got done and when. He said that following the Aisling tragedy, his firm's CCTV crews could directly communicate with the council.

Mr Coe said his company now alerted police to any drain work in the vicinity of a search and rescue operation.