Close-up of 4mm Offtakes, by Plassay, Yates, obtained from a garden center. As the bottle fills with water, air escapes around the connector in the lid. This is necessary so pressure does not build up until the bottle is filled with water. Water drips out two small holes in the base of the plastic bottle. The bottle is mostly buried. I set the timer for 20 minutes. The tap-timer turns off the water after 20 minutes and my drippers keep irrigating the garden under the surface in the heat of the day. Turn on and I walk away! Let me know if you have an improvement on this. I have changed my drip system. I now use large plant pots with sand or soil in the bottom. They already have holes in the pots so water can drip out and this is slowed by the soil. I partly bury the bottom of the pots too to encourage subterraneous irrigation. Leaching Concerns PET and BPA plastics are the most common types of containers for water and other drinks. Both PET plastics and BPA plastics have been shown to leach over time. PET plastics tend to leach when exposed to realistic though extreme conditions, such as exposure to sunlight, heat and storage time (see References 4). The Harvard School of Public Health has shown that exposure to BPA can interfere with reproductive development in animals. It has also been linked with cardiovascular disease and diabetes in humans (see References 3). snip I'm