How to make a cheap Rain Gauge

Read this nice blog about How to make a cheap Rain Gauge. Rainfall measurement is very helpful in understanding the weather around you. For example if you want to harvest rainwater, understanding rainfall patterns and quantities helps to get a good design for the storage and recharge. Here is how you can make a cheap rain gauge and start putting it to use this monsoon. You need a 1 litre or a 2 litre PET or PVC bottle. The bottle should have a flat base and be vertical for the most part.