Bumpa should contain good quality water.

Everyday, whenever an offering like sang, incense sticks, butter lamp, water, fruits, Serkim, Sur etc are made at the altar, it has to be purified first by sprinkling water (yongchap) from the Bumpa. If yonchap is not done, offering remains ineffective.

Therefore, it is obvious the water that is stored inside the Bumpa should be of exceptional quality. It has to be clean and if possible a mixture of few drupchhus.

If possible I do use the following drupchus: 

1. Water from River Ganga (India)
2. Tsheringmo Drupchu, Trongsa
3. Terton Drukdra Dorjee’s Drupchhu, Damchu
4. WalaGyelpo Drupchhu, Lobesa
5. Penzo Gyelmo Drupchu, Thinleygang
6. Je Ngawang Drukpa Drupchhu, Dhamchu
7. Saffron (Kesar) and Bumpa rilbu.
8. Champor

So you can also try!

Generally, the bumpa contains the blessed water (which may contain saffron or medicinal ingredients) and the peacock feathers fit into the top of a conical tube the bottom of which sits in the water in the bumpa. The tube (with the feathers on top) is taken out and flicked or shaken and the residual water in it is used to bless the shrine or whatever.

In case the Bumpa is used for purification, the water has a cleansing effect. 
The peacock feathers do symbolize the peacock that can eat poisonous snakes. It is symbolizes purification (transforming). Tantra is based on transforming.

Also during Tantric rituals the Bumpa is used.
It symbolizes then the power etc. of the Yidam in the one or other initiation aspect of His/Her/Their Mandala.