The Solinst Waterloo Emitter is a passive, non-mechanical device installed in a well or borehole to slowly release a gas or dissolved amendment into groundwater. Silicone or LDPE tubing is coiled around a rigid PVC frame, and a supply gas — oxygen, hydrogen, CO2, or a tracer gas — is fed under pressure into the coil from a surface cylinder and regulator. Because the tubing wall is gas-permeable, the amendment diffuses outward through the tubing according to Fick's Law wherever a concentration gradient exists; since groundwater continuously flows past the coil and carries the diffused gas away, that gradient is never eliminated, so diffusion continues as long as gas is supplied. Higher supply pressure increases the release rate, and because gas leaves only by diffusion through the tubing wall rather than by bubbling or venting, amendment loss as escaping gas bubbles is avoided.