Rumney opened with a try by Stuart McIntyre, but then fell behind when fly half Mark Roper crossed for a try that Marc Davies converted. Continuous attacking saw Llanharan lead 29-5 at the interval and they finished with 11 tries in a 63-5 win. Roper added two more and Richard Emms (2), Colin Malone (2), Lee Davies, Marc Davies, Christian Perry and Nicky Morgan all scored with Marc Davies kicking three more conversions.
Marc Davies became the first player to Waes to pass 450 league points this season and his club now go to Carmarthen Athletic on Saturday needing a point to win the Divisional title.
Also in Division One, Brynmawr confirmed their fine fifth position by winning 25-22 at Blackwood with Jason Williams kicking ten points and tries coming from Simon Parry, Richard Dennington and Jonathan Pleece.
Builth Wells captured the East title with one match still to play after gaining a 103-0 win away to bottom club Penygraig. The Bulls took complete control and helped put the points against total to ver 2,000 points for the losers.
In the West, Bridgend Athletic's 46-3 win over Felinfoel has left them needing a win away to Newcastle Emlyn on Saturday to jump them over Dunvant in second place behind champions Tonmawr. Bottom club Aberavon Quins put up a game display, but went down 34-20 at home to Cwmavon.
The fight for the East title became even tougher and more confusing after leaders Senghenydd went down 10-5 against Old Illtydians at Llanrumney Park and Brynithel join them with 51 points after winning 27-0 away to top club Brynithel. New Tredegar continued their late run by defeating Talywain 57-13.
Senghenydd and Brynithel are joined in the title race by Newport saracens and Llanishen, who meet tonight at Newport's Civil Service Ground. Abercarn and
Pontypool Utd are both safe from relation and Pooler were 21-17 away winniners in their clash at Abercarn.
In the West, Haverfordwest kept ahead of visitors Lampeter after a 24-20 home win and in the South-West, champions Banwen played their penultimate league match to defeat Nantyffyllon 22-10.
Rhyl moved up a place in the North, jumping over Wrexham, after gaining a 27-16 away win over Caernarfon.