You need Cheat Engine for this hack to work.
do the following steps.
1- Open Farmville 2 and Cheat Engine
2- In Cheat Engine Click on ( Select a process to open)
3- If you are playing Farmville 2 on Google Chrome , Select any one of your Google Chrome process. If playing on Firefox Select Firefox or Select Flash files.
4- Change Value type to String.
5- Go to your Farm and buy ”Mister Scraps” from market. Place as many as water tough you want.
6- Now back to Cheat Engine and paste this code into text area > e_deco_scarecrow_generic
7- Click on First Scan.
8- You will see all the Results on Left side . Select all results and Drag Down all the Results .
9- Select all Drag objects and change “value” to > e_building_watertrough_3
10- Store all the ”Mister Scraps” and refresh your farm.