PLEASE READ THIS CAREFULLY BEFORE BUYING OTHERWSE THE PRODUCT WILL NOT WORK :Firstly, please make sure which 20 litre bottle you are using. There are 2 types of bottle necks - one is threaded one (for bisleri) and the other one is plane and non-threaded. So for threaded neck bottle (like bisleri) you need to fix the provided white adapter at the bottom of the pump by pressing it, then put this pump on the neck of bottle and rotate it few times to fit it tight. For non-threaded neck bottle (for brands other than bisleri), you just need to put this pump without adapter on neck of bottle and press it hard till you hear the fitting sound. Make sure the fitting is tight and there is no vacuum for air to leak otherwise the water will not pump. Now start pressing the pump few times and water will start flowing. Hope this helps.PS : The white adapter is only provided for threaded bottle necks like bisleri. For non-threaded bottle necks, ie. for brands other than bisleri, please don’t use this adapter otherwise water will not pump.Overview :With the increasing use of large water barrels due to hygiene reasons, a solid water dispensing solution is the need of the hour. Featuring a unique and effective manual dispensing action, the hand press manual water dispenser pump fits the opening of all 20 to 25 litre water barrels for ease of use. With an innovative vacuum action, you can instantly gain access to water without having to tilt or move the barrel. This pump is ideal for use in homes, offices, hospitals, schools or even on camping trips.The manual water dispenser pump features an effective design that makes pumping water a hassle free process. To use this pump, simply fit it properly on the mouth of the water barrel and press around 5-6 times to get a steady water flow from the specially designed outlet. To facilitate easy cleaning, this dispenser pump features a removable tube.