The wall, a portable backyard fence, is to be taken around New Zealand, collecting signatures for an initiative against drugs in sport.
Loader was Otago's leading sportsman in the 1990s and won two Olympic gold medals in swimming at Atlanta in 1996.
Rower Mahe Drysdale and former rugby league forward Monty Betham will be the first to sign when the wall is officially unveiled during the opening ceremony of the New Zealand College Games in Hamilton.
Loader will join participants and members of the public in a wall-signing session during the athletics at Porritt Stadium tomorrow.
Other elite athletes, including Olympic champion Caroline Evers-Swindell, have signalled their support for the project.
After the College Games the wall will be taken to major centres throughout New Zealand.
The Pure Playing Field Nation is an initiative of Drug Free Sport New Zealand, aimed at reinforcing a drug-free culture at all sporting levels from top performers to beginners.
"This year has seen some great steps forward for Drug Free Sport," drug education programme manager Andrew Sylvester said.
"Almost every member of our Olympic squad and many other sports stars have signed our pledge, committing themselves to staying drug-free and entitling them to wear a distinctive green wristband. We expect that huge numbers of New Zealanders will agree with us and will want to add their names to the wall."
Drug Free Sport New Zealand chief executive Graeme Steel described this country as having a predominantly clean sporting culture but said internationally there were tremendous press-ures on athletes to use drugs.
"We need to buffer the next generation against these pressures and provide them with tools to resist," he said.
The New Zealand College Games were first held in 2000 and are staged every four years at Hamilton.
The Olympic-style event involves 20 sports and about 3000 participants from 250 schools.
Most of the individual sports have their own annual championships, with the national secondary schools athletics championships first held at Christchurch in 1973.
