MUD\WTR is showing a 43% off starter kit promo as the main offer, available via the 43% off voucher at the top of this page, and that is best for anyone who intends to buy the Starter Kit. If you want something other than the Starter Kit the sitewide 15% off coupon is the next straightforward option and is better when your cart contains multiple full price items.
Small single item order (buying the Starter Kit only): Use the 43% off voucher at the top of this page, because it specifically discounts the Starter Kit by 43%. On a $120 Starter Kit, for example, the 43% discount takes $51.60 off, leaving a final price of $68.40. The 15% sitewide coupon would only take $18 off that $120 Starter Kit, leaving $102, so the 43% voucher saves more.
Small single item order (buying any other single item): Use one of the 15% off coupons. Those coupons take 15% off sitewide or on your order as described, so on a $30 item you save $4.50 and pay $25.50. The 43% Starter Kit voucher will not apply to other items.
Medium cart with several full price items (for example $120 total of mixed items): Use the 15% sitewide coupon, which takes 15% off the whole cart. On a $120 order that reduces the total by $18 to $102. The Starter Kit code only applies if the Kit is the product being purchased.
Large cart (higher spend, for example $300): The 15% coupon is the relevant choice, taking $45 off a $300 cart and leaving $255. The 43% Starter Kit voucher does not help unless your basket is one Starter Kit.
Newsletter sign up: If you are a first time customer who prefers a signup discount, sign up to the newsletter for special offers and promotions; that is a route for future or new customer offers but it is not the page lead coupon and is only mentioned here for low spend or first order circumstances.
Our records show the 43% code on this page matches the biggest percentage code our database recorded in the 12 months to October 2026, and the largest sale in that period reached up to 50% off. Our team performed 2 checkout tests across 2 offers in the 12 months to October 2026, with screenshots kept as proof.
To choose between the coupons that apply to your basket, compare the final cart totals and take whichever leaves the lower total. Several of the 15% coupons state they cannot be used with other offers in their terms, so do not expect to stack them with another coupon; where terms are silent no combination rule is stated here.