1. Tsev kais dej lim
Hauv nroog, kais dej muaj ntau yam impurities. Siv lub tshuab nqus hlau nplaum tuaj yeem tshem tawm cov impurities zoo, ua rau cov dej kais dej huv dua thiab nyab xeeb rau cov neeg siv khoom.
2. Lub pas dej da dej lim dej
Siv lub tshuab nqus hlau nplaum hauv lub pas dej da dej tuaj yeem tshem tawm cov impurities xws li xuab zeb thiab pebbles, ua kom cov dej ntshiab thiab huv dua.
3. Cov ntawv thov kev lag luam
Cov ntxaij lim dej sib nqus kuj tau siv dav hauv kev lag luam xws li kev ua hlau, tshuaj, thiab khoom noj khoom haus. Lawv tuaj yeem tshem tawm impurities zoo thaum lub sijhawm tsim khoom, txhim kho cov khoom zoo.