Alton, after a below-par first half on Saturday, took their lowly opponents apart to keep the pressure right on leaders East Cowes Vics.
East Cowes came from behind to beat Winchester City 3-2 in the top-of-the-table clash, but Alton have a match in hand and are just one point adrift of the leaders.
On a very bumpy Bass Sports Ground pitch, Bishops Waltham got plenty of men behind the ball and looked to hit Alton on the break.
Town were hurrying their football and lacked inventiveness in this half, hardly looking like a side challenging for league honours.
Manager John Robson clearly gave his players a rocket at the interval because Alton were transformed in the second half.
Within minutes, Ian Dyer played in a pin-point cross from the left and Jason Dinham volleyed home from 15 yards.
Although Paul Lloyd had to go off injured, Alton had woken up with a vengeance. Darren Bach was back in goal after a six-week absence through injury and Micky Street, his excellent stand-in, was able to play an important role in midfield.
Central defenders Dave Goss, Nicky Guy and Andy Sharratt are getting meaner by the week and this was Alton's seventh consecutive clean sheet.
Another good cross from Dyer led to the second goal, Steve Poulton being pulled down just as he was about to stroke the ball into the net. The Waltham centre-half was sent off and Jamie Smith scored from the penalty spot.
The prolific Poulton was not to be denied and, with Alton using the extra man to good advantage, scored his customary goal. Andy Sharratt crossed accurately from the right and Poulton, controlling the ball beautifully, turned inside the six-yard box to shoot home.
Alton rounded off a fine second-half display when Clive Ventham set up Poulton for his second goal and the home side's fourth.
Substitutes Mark Dando and Richard Melia looked good in the last 20 minutes.
Alton are at home again this Saturday and will be looking to extend their superb run by beating Stockbridge.