The result was Ngongotaha's second win of the grading round and the Rotorua team will find out later this week if they have done enough to secure one of the two spots left for the Premier grade competition.
"There's plenty of positives to take from our first three matches," said Nahu. "We have a good nucleus and structure in the team which we'll look to build on in weeks to come."
Elsewhere Pikiao Warriors, who had already secured a spot in the Premier division, fell to a 24-10 loss to Otumoetai Eels Premier, in section one, at Mitchell Park.
It was a disappointing defeat for head coach Jason Parata after his side went in with a 2-0 lead at half-time.
"In the first half our defence was great and we really stood up, but after the break a few errors started creeping in and we went away from what we had been doing," he said.
It was Pikiao's second defeat in the grading competition - but the confident coach said he was pleased with progress made over the last three rounds and picked out Pacific Sharks Premier and Otumoetai as teams to watch out for.
"It's good that we've been able to check everyone out and see what they're about," Parata said. "Pacific look very strong and Otumoetai are a class act.
"We're in with a good chance to challenge for the title and I have confidence in the players - we just need to be more consistent and have less errors cropping up."
BOPDRL and Coastline combined district competition
Grading games - round 3 results:
Section 1: Taupo Phoenix Premier 18 Pacific Sharks Premier 56
Otumoetai Eels Premier 24 Pikiao Warriors Premier 10
Section 2: Taupo Phoenix reserves 8 Pacific Sharks reserves 48
Otumoetai Eels reserves 30 Pikiao Warriors reserves 16
Section 3: Ngongotaha Chiefs 46 Taneatua Warriors 24
Putauaki Stags 14 Mangakino Hawks 54
Section 4: Papamoa Bulldogs v Tauhara te Maunga (score unavailable)
Te Teko Bulldogs - bye.