Linen

Linen is one of the oldest fabrics on earth, and one of the strongest (it also becomes 10% stronger when wet!). It's also hypoallergenic. 
One shirt takes about 6.4 liters of water to produce, from seed to product, making it the most water conscious fabric. 85% of the worlds linen comes from Europe. The climate of linen producing countries is ideal for growing flax without the need for irrigation or pesticides.