Cut the bacon into chunks and place in slow cooker dish. Cut the leeks and place into the dish. Cut the potatoes into small chunks and place in the dish.
Add water so that it is just visible and not over the top of the ingredients. Add as much mixed herbs as you want.
Cook on high for 4 hours or on low for 8 hours.
Once cooked remove approx 1/2 to 2/3 of the ingredients from the dish (depending on your preferred thickness). Drain into a pan and place the drained liquid back into the slow cooker, leaving the removed ingredients in a colander.
With a hand blender blitz the remaining contents of the slow cooker pot into a thick soup. Once blitzed, replace the removed ingredients. Give it all a stir and serve.
If you feel the blitzed soup is a little too thick, add some hot water from the kettle to thin it back out a little.
If its a little too thin, add some more of the removed ingredients and continue to blitz.