Why you should always use liquid detergent - CNET- powder Machine wash detergent laundry soap washing soap powder ,Powder can also leave chunks of undissolved detergent in your washing machine parts. As you can imagine, this can lead to malfunctions. It particularly affects the washer's drainage system.Liquid or Powder Washing Machine Laundry Detergent? You ...On the down side of using powder detergents, they can contain more chemicals than liquids and the sodium sulfate in most detergents can cause problems in septic tanks. Liquid detergents are already pre-dissolved and start washing as soon as it comes in contact with agitated water. You can also get rid of stains better with liquid detergents ...