Very hard water area - how d'you get your flannels & towels clean?

[Soberlober]

I'm getting fed up of towels & especially flannels that develop a grey area in the middle where they don't come clean properly. I think it may have something to do with us being in a hard water area. There's no possibility of attaching a softener to the washing machine so what else can I do? What products/systems do you have to guarantee spotless flannels?

Do you use blue shower gels? We had that issue with staining from this.

95c wash, soda crystals and bio soap liquid.

do you wash them warm enough?
what detergent do you use?

Another shout for soda crystals here. Keeps everything clean and fluffy. Our water is VERY hard.. bubble baths are almost impossible

How much soda crystals do you add to the wash? I've never used those before.