Method handleWaterMovement

src/main/java/net/minecraft/entity/Entity.java:1130–1149

Returns if this entity is in water and will end up adding the waters velocity to the entity

()

     * Returns if this entity is in water and will end up adding the waters velocity to the entity
     */
    public boolean handleWaterMovement()
    {
        if (this.worldObj.handleMaterialAcceleration(this.getEntityBoundingBox().expand(0.0D, -0.4000000059604645D, 0.0D).contract(0.001D, 0.001D, 0.001D), Material.water, this))
        {
            if (!this.inWater && !this.firstUpdate)
            {
                this.resetHeight();
            }

            this.fallDistance = 0.0F;
            this.inWater = true;
            this.fire = 0;
        }
        else
        {
            this.inWater = false;
        }

        return this.inWater;
    }

    /**
     * sets the players height back to normal after doing things like sleeping and dieing