Hoeptner Perfected Products offers the FreezeFlow yard hydrants in standard and executive models. The standard hydrant design is based on a venturi principal. When the hydrant is off, the stopper seals against the nozzle and stops the flow. The remaining water in the riser drains back into the canister below the frost level, preventing freeze-ups. When the hydrant is on, the flow through the nozzle creates a vacuum in the canister and flows all the water out the hose bib. The executive model does not require winterizing and works on a piston principal, which forces stored water out of the reservoir each time it is operated, regardless if a hose or backflow preventer is used. Both models prevent cross-contamination, will not contaminate the water supply or ground water, and are fully self-contained. Hoeptner Perfected Products.