Van der Merwe helped Gregor Townsend's side romp to an emphatic 60-3 win over Dragons in South Wales last Friday in the Rabo Direct Pro 12.
The eight-try annihilation was the biggest in the history of the club and kept them in second spot in the league table just ahead of Leinster.
With a massive showdown against leaders Ulster looming at Scotstoun later this week, the one-sided victory was timely.
But Canadian winger DTH, who has agreed a two-year extension to his contract at Warriors, still feels there is room for improvement.
He said: "We didn't expect the result against the Dragons at all. We had prepared all week for a very tough battle.
"Gregor said to us that it had been about five years since any Scottish team, either Edinburgh or Glasgow, had won away against Dragons.
"We were expecting an awful fight, especially up front. Fortunately, luck was on our side."
"But if we had played a different team on the same night then I think it would have been a different story.
"We are always looking to improve the team and we still have a lot of work to do at the breakdown and in other areas and can still play better."
The 26-year-old is hoping Glasgow fans turn out in numbers at Scotstoun on Friday for their showdown with Ulster as a result of the win.
Van der Merwe added: "This week's game is massive for us and for the league. You have the first placed team playing the second placed team and the third placed taking on the fourth placed.
"I would say it is our biggest game of the season. We have played Ulster three times this season and have lost three times this season.
"But we will go into it on the back of two bonus-point victories over Zebre and Dragons and hopefully the fans will come out and cheer us all on."
Van der Merwe, who can become Glasgow's all-time record try scorer with two touchdowns against Ulster, reckons the hunger of the fringe players can help them against Ulster.
He remarked: "The players who have not been getting a game this season have really taken their opportunity while the internationalists have been away with Scotland.
"We have used 50 players now this season. I think that shows we have got a strength in depth that perhaps we did not have before."