Provided are methods and systems for dispensing different chemicals used for high productivity combinatorial processing. A dispense panel may include multiple inlet lines for supplying different chemicals. Each inlet line is connected to its own three-way valve that either allows the supplied chemical to flow from the inlet line towards a dispense valve connected to a dispense manifold (during dispensing of the supplied chemical) or allows another chemical to flow from the dispense valve to a waste manifold (during priming of the dispense manifold with this other chemical). Specifically, during priming a chemical supplied from its inlet line and is passed through a corresponding three-way valve and is directed to its dispense valve and then into the dispense manifold. Other dispense valves and three-way valves of the dispense panel allow this chemical to flow out of the dispense manifold, thereby priming remaining parts of the panel.