It is 10 points clear of its nearest rival and on a 12-game winning-streak.
Kaikorai brushed aside Zingari-Richmond 60-22 thanks to some fine back play and smart use of the wind.
Green Island's slim semifinal prospects were snuffed out by Taieri as the Eels won 30-6.
Dunedin beat Alhambra-Union 48-32 and remains in fourth place. Southern smashed Pirates 62-11 but is still three points outside the top four.
University 26
Harbour 22
University scored three tries in a 10-minute purple patch to beat Harbour 26-22 in a hard-fought top-of-the-table game at Watson Park.
Harbour had the better of the first spell to lead 15-7 at the break and looked to have the game in its grasp when PJ Tili scored after 15 minutes in the second spell to stretch the lead to 22-7.
This setback sparked the students into action and they scored three tries in the next 10 minutes to take the lead for the first time in the game.
Centre Shae Tucker scored a long-range 70m try and was the pick of the student backs.
He was supported by wing Gavin Stark, who scored his 15th try of the club season, while replacement halfback Harry Peeters impressed with his long passing in the second spell.
The best student forwards were rampaging lock Josh Dickson and hooker Sam Sturgess.
The strong Harbour forwards were efficiently led by No8 Ben Whale and had the edge for most of the game.
Whale was backed up by lock Hale T-Pole, flanker James Tomkinson and hooker Sekonaia Pole.
The best Harbour back was centre Ewan Brumwell, who scored an impressive long-range first-half try, and first five-eighth Joe Collins.
Kaikorai 60
Zingari-Richmond 22
With a bit more thought Zingari-Richmond might have pushed Kaikorai a little closer at Bishopscourt.
You did not need a firm grip of advanced mathematics to figure out the wind would be quite helpful.
The first hint came when Kaikorai fullback Tony Ensor carved off plenty of territory every time he booted it during the opening 40 minutes.
When he ran he was dangerous as well. And while he did not get on the scoresheet, he was instrumental in putting his side in good positions.
Zingari-Richmond opened the scoring with a penalty but Kaikorai centre Danny van der Voort scored shortly after his side attacked down the right and found plenty of space.
Zingari-Richmond loosie Tom Rowe was dynamic in the lineout and snaffled his share of possession, but he was powerless to stop Kaikorai's second try which came from a nice lineout drive.
Johnny Appleby was at the back when his side crossed the line.
The visiting side added a fourth try just before the break when a Neil Brew pass was picked off by Mitch Purvis.
Despite trailing 26-3, the Colours had the wind at their backs and certainly were not out of the contest.
Had they played the territory game and plugged the corners instead of trying to run the ball out, perhaps Kaikorai might not have been able to add six second-half tries and run away with a comfortable win in the Challenge Shield match.
Taieri 30
Green Island 6
Green Island needed to beat Taieri to keep alive its slim chances of reaching the semifinals but came unstuck at Miller Park.
The game did not rise to any great heights but Taieri did defend well and most of its opportunities were created through stout defence.
Green Island got on the scoreboard first through a penalty to Alex Barnsley.
Michael Collins responded with two penalties and Barnsley kicked another to level the scores.
The key moment in the opening half came when Green Island lost possession.
Taieri spun it wide and midfielder Vinnie Booiman strolled across and dotted down close to the posts.
Taieri added to its halftime lead of 13-6 when loose forward Brodie Hume crashed over following a period of sustained attack.
The game got messy following Hume's try with both sides making crucial mistakes.
Green Island arguably had the better of the second spell but was kept scoreless thanks to some tenacious defence.
The killer blow came when Mitchell Scott grabbed an intercept and ran 85m to score midway through the period.
That effectively sealed the win but Taieri was able to find a fourth try right on the stroke of fulltime.
Green Island had been battering away at the line but Taieri swooped on a mistake and Taylor Fiddes scored.
The final margin was flattering but Taieri earned the win.
Southern 62
Pirates 11
Southern overcame some first-half blues for a commanding 62-11 victory over a plucky Pirates side at Hancock Park.
A dominance of territory and possession had Pirates very much in the game heading into the break.
Only a lapse in discipline paved the way for Southern No8 Junior Sala to score under the crossbar from a penalty tap kick, and blow the score out to 19-11 at the break.
Until then, Pirates had played with commitment, leaping out to an 8-0 lead after 16 minutes.
Yet despite a generous amount of possession, Pirates was unable to further penetrate the solid defensive screen of Southern.
Its three first-half tries came from rare incursions into the Pirates' half.
There was a much improved performance from Southern in the second half, as its backs ran rampant, and the forwards deprived Pirates of the ball it enjoyed in the first half to run in a further seven tries.
Josh Ioane had a superb game. He took over the reins at first five-eighth midway through the first half and got wonderful service from halfback Josh Walden.
Despite the score, there were plenty of positives for Pirates. New recruits Rewi Pomare and Jonathan Ruru were two of its players to feature.
Dunedin 48
Alhambra-Union 32
Dunedin started the game with a hiss and a roar at Kettle Park and had a try on the board within two minutes when fullback Henry Scott scored out wide from a quickly taken penalty.
He scored three tries in the game and was Dunedin's most dangerous back.
Dunedin then conceded a sloppy try when a stab kick went straight into the hands of Alhambra Union halfback Legin Felix-Hotham who scampered 30m to score and tie up the game.
Dunedin was four tries up by halftime, with the bonus point, and when it ran the phases down looked unstoppable.
But brain fades and handling errors allowed Alhambra Union to stay in touch and it was only down by 14 points at the break.
Early in the second spell, the the visiting side turned over the ball and fast hands put winger Adam Simpson over out wide.
Dunedin put the game beyond reach on the back of its increasingly dominant scrum and replacement No8 Lausei Pritchard dotted down from a pushover.
Winger Guy Woodhouse scored after a 12-phase series left Alhambra-Union with no numbers and the game was over as a contest.
Alhambra-Union winger John Tapueluluheu scored two late tries with some nice skills and pace but he was aided by some incredibly bad Dunedin defence to add some respectability to the score.
Right on fulltime, fullback Scott added his third try for Dunedin to nearly hit 50.
As per usual, lock Mark Grieve Dunn and loose forward Hame Toma were Dunedin's best and were ably supported by Donald Brighouse and Eliot Adamson in the tight.
Tapueluluheu was the best back for Alhambra-Union but halfback Felix-Hotham and midfielder Rhys Morgan had good moments. Lock Ryan Dawson battled away manfully up front.
