How to clean out this soap barrel?

[wahoowad]

I am going to make a water tank that will fit in the bed of my truck for watering my garden. I picked up a 20 gallon plastic tank from a car wash place that originally held car wash soap. It still has some residual soap in it and I want to thoroughly flush it out before using it to water the garden. Any idea on how to do this?

I can run some water through it using a hose but I figure it will foam up and continue to leave bubble/soap residue. Is there something I can pour in the help break down the soap or otherwise cut through it to help flush it out?

 

[Backwoods Savage]

Bleach and water.

 

[wahoowad]

Any recommendation on ratio of bleach to water? I could probably pour 2 or 3 gallons of hot water in there and give it a long shake.

 

[kettensäge]

We used to use a 100 to 1 bleach water concentration at work to sanitize detergent filling machines.
The warmer the water the better. Allow some contact time, 20 mins to 1/2 hour, repeat as needed.

If it was ordinary soap and not too agressive the residual soap shouldn't hurt the garden, You can use a soapy water mix to keep certain bugs away.

You can get defoamer where they rent carpet cleaning machines, but it is made of silicone and just kills the foam, doesn't remove the soap, probably not so good for the garden.

 

[wahoowad]

I cut the top off one of these soap barrels previously (basically made a large tub) so that made it very easy to wash out all the soap. But this barrel will only have two 2-inch openings in it so I am mostly stuck with flushing it out with a hose and/or using some kind of non-poisonous liquid to help break down the soap. So goal is to break down or otherwise cut the soap so I can flush it out easier.

 

[kettensäge]

A bleach rinse should do it, followed by a complete water rinse to remove the bleach. The caustic nature of the bleach will breakdown any soap left in the barrel. Residual bleach will evaporate if not removed by the rinse.
What type of soap was in the barrel?

 

[benjamin]

I hold them upside down or at a steep angle with one hole at the bottom and spray through the other hole with the hose to get most of it out. Then leave it under the eaves of a shed to fill with rain water and dump periodically until you're satisfied it's clean enough.

 

[Delta-T]

in some cases, the emulsifying power of soap can be useful in the soil. it can kill/deter many creepy crawly things and helps overworked soil to hold water. I add a drop or so of dish soap (non-antibacterial) to my houseplant sprayer every now and again and the rate of water absorption definitely increases with some of the older pottings. Not sure how aggressive the soap you have is though.